Month by Month Weather and Wildflowers
- Seasonal Summary
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- Winter
- 2005: abundant rain, no snow, warm temperatures
- 2006: drought with first rain and snow in March
- 2007: rain, snow and unusually cold
- Spring
- 2005: no rain
- 2006: rained once in April, no rain in May, early monsoon start in June
- 2007: started cold, periodic rain, windy; ended hot, rain once in June
- Summer
- 2005: heavy monsoon rains started mid-July and ended early September
- 2006: a long monsoon with heavy rain, frequent winds and hot
- 2007: warmer and drier than normal, humid, windy, little heavy rain
- Fall
- 2005: severe drought with one rainfall, heavy, in mid October
- 2006: very dry except rain and hail in October
- 2007: normal rain pattern but drier, then abundant rain in December
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- Overview
-
Arizona weather is determined by two large-scale Pacific Ocean patterns involving wind and ocean currents.
These Pacific weather conditions, named La Niña and El Niño, cycle unpredictably between
each other.
The El Niño weather pattern, which brings abundant rain to Arizona, occurs irregularly every
two to seven years. The La Niña weather system provides our normal drought.
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- January
-
Precipitation in January varies from none to abundant rain and snow lasting up to two days.
Temperatures are mainly in the thirties to forties at night and forties to fifties during the day.
Freezing temperatures at night are not uncommon. Strong winds and overcast skies can be expected
one day out of three.
Plants in bloom: Manzanita, Rosemary,
Winter Iris (blue flowers on 6" stalk).
The best-looking native evergreen shrubs are Turpentine Brush (with rain)
and Desert Broom.
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- February
-
Precipitation in February varies from none to rainfall several days one or more weeks.
Snow or sleet may occur one or more days.
Temperatures, in a warm winter, range from the forties at night to the fifties to sixties in the daytime.
Temperatures, in a cold winter, range from the thirties to forties in the early morning and forties
and fifties during the day.
Plants in Bloom by Color
- Blue:
- Rosemary
- Magenta / Purple:
- Filaree
- Orange:
- Desert Globemallow
- White:
- Desert Anemone, Manzanita, Stemless Daisy
- Yellow:
- Bladderpod Mustard
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- March
-
It usually rains several days throughout March. In some years, it may snow on more than one day.
Snow normally melts within 12 hours, but has lasted as long as two days. Snow can often be seen on Mount
Lemmon lasting several weeks.
Strong winds and overcast days are not uncommon. In warm winters,
night-time temperatures ranging from the forties to fifties and daytime temperatures in the sixties
to eighties.
In cold winters, night-time temperatures are in the twenties to thirties and daytime temperatures in the
forties to sixties. Over any 24 hour period in March, high and low temperatures can vary as much as 25°F
although 20°F is the norm.
Plants in Bloom by Color
- Blue:
- Blue Dicks, Blue Toadflax, Chia,
Desert Lupine,
Miniature Wool Star, Rosemary, Vinca Major, Wild Heliotrope
- Green:
- Rabbit Thorn
- Magenta / Purple:
- Dakota Verbena, Elegant/Bajada Lupine, Filaree, Henbit,
Texas Ranger
- Orange:
- Desert Globemallow
- Pink:
- Fairy Duster, Shrubby Coldenia (red, pink, white),
Stiffarm Rock Cress
- Red:
- Paintbrush (Castilleja integra), Scarlet Bugler (Penstemon subulatus)
- Varied:
- Iris, Tombstone Rose
- White:
- American Carrot, Bush Morning Glory, Desert Anemone, Desert Ceanothus,
Desert Chicory, Dryopetalon, Fleabane, Manzanita, Narrow-Leaved Popcorn Flower, Tackstem (white or pale
yellow)
- Yellow:
- Bladderpod Mustard, Bottle/Desert Evening Primrose (blooms only one night),
California Poppy, Desert Marigold,
Emory Oak, Euphorbia Rigida, Fiddleneck, Fringed Gromwell,
Green's Lotus, London Rocket, Silver Puffs, Three-Leaf Sumac, Winter Jasmine,
Yellow Linanthus
Of all the native plants in bloom, Blue Dicks, California Poppy, Desert Lupine, Paintbrush and Scarlet Bugler
are the most colorful this month.
Wild honeybees swarm in the spring, and a migrating swarm may temporarily "rest" for a day
on your property. Leave them alone and they will move on.
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- April
-
There may be no rain to rainfall nearly once a week in April. It seldom, if ever, snows.
Low temperatures are in the thirties and forties at the start of the month and in the forties and fifties
by the end. Freezing temperatures in recent years have been recorded as late as April 22.
High temperatures, in the first two weeks, vary from the sixties in cold years to the seventies in warm years.
High temperatures at the end of the month are in the seventies to eighties.
April shows a clear transition between winter cold and summer heat,
with rising temperatures interrupted by the occasional cold front.
Low and high temperatures can vary as much as 30°F in one day.
Strong winds are common.
On a few days sustained wind speeds of 25-30 mph will last an entire day with wind gusts up to 45 mph.
Plants in Bloom by Color
- Blue:
- Blue Dicks, Blue Toadflax, Desert Lupine, Miniature Wool Star,
Paleface Delphinium, Rosemary, Scurf Pea,
Wild Heliotrope
- Green:
- Antelope Horns (green and maroon), Desert Pipevine (green and brown),
Hollyleaf Buckthorn (green or green-yellow), Rabbit Thorn
- Magenta / Purple:
- Bajada Lupine, Dakota Verbena, Desert Four-O'clock, Filaree,
New Mexico Thistle, Purple Aster, Rainbow Cactus, Range Ratany, Ribbon Four O'clock,
Sand Verbena, Silver Leaf Nightshade, Strawberry Hedgehog,
Trailing Indigo Bush
- Orange:
- Aloe saponaria,
Desert Globemallow, Desert Mariposa, Engelmann's Prickly Pear,
Littleleaf Globemallow, Sida
- Pink:
- Arizona Penstemon, Fairy Duster,
Perezia
- Red:
- Paintbrush (Castilleja integra), Red Yucca, Salvia greggii, Scarlet Bugler (Penstemon subulatus)
- Varied:
- Iris, Tombstone Rose
- White:
- Banana Yucca, Bush Morning Glory, Cream Cups, Desert Ceanothus,
Desert Chicory, Desert Onion, Elderberry, Fleabane,
Hall's Honeysuckle,
Horehound, Manzanita,
Narrow-Leaved Popcorn Flower, Sego Lily, Stemless Primrose,
Tackstem (white or pale yellow), Tufted Globe Amaranth,
White Aster, White Margin Spurge, White Nightshade, White Prickly Poppy
- Yellow:
- Bahia, Broom Snakeweed, Bottle/Desert Evening Primrose (blooms only one night),
California Poppy,
Desert Marigold, Desert Mariposa,
Emory Oak, Engelmann's Prickly Pear, Fiddleneck, Goldfields, Golden Columbine, Green's Lotus,
Mormon Tea, Needleleaf Dogweed, Paperflower, Reddome Blanketflower, Silver Puffs,
Thick-leaved Ground Cherry (Ivyleaf Groundcherry), Three-leaf Sumac,
Western Wallflower, Winter Jasmine, Yellow Linanthus
The most commonly visible native wildflowers are Broom Snakeweed,
Dakota Verbena,
Desert Globemallow, Desert Marigold,
Fairy Duster, Fleabane,
Miniature Wool Star, New Mexico Thistle and Wild Heliotrope.
Green fruit of Manzanita and Three-Leaf Sumac start turning red during the month.
Wild honeybees swarm in the spring, and a migrating swarm may temporarily "rest" for a day
on your property. Leave them alone and they will move on.
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- May
-
On average, May is the lowest rainfall month of the year. Rain may vary from none to nearly
once a week.
Low temperatures are in the forties and fifties at the start of the month and in the fifties to low
sixties by the end.
High temperatures are in the sixties to eighties at the start of the month, and eighties to low nineties
at the end. Low and high temperatures in a typical day vary by 30°F.
Most days are windy with occasional strong gusts. On a few days sustained wind speeds of 25-30 mph will
last an entire day with wind gusts up to 45 mph.
Plants in Bloom by Color
- Blue:
- Arizona Blue Eyes, Desert Lupine, Miniature Wool Star, Scurf Pea,
Small Wirelettuce, Wild Heliotrope
- Green:
- Antelope Horns (green and maroon), Desert Pipevine (green and brown),
Hollyleaf Buckthorn (green or green-yellow)
- Magenta / Purple:
- Cane Cholla, Dakota Verbena, Desert Four-O'clock, Filaree,
New Mexico Thistle, Rainbow Cactus, Range Ratany, Ribbon Four O'clock, Silverleaf Nightshade,
Strawberry Hedgehog, Tansyleaf Spine Aster, Trailing Four O'clock,
Trailing Indigo Bush
- Orange:
- Copper Purslane,
Desert Globemallow, Engelmann's Prickly Pear, Littleleaf Globemallow,
Sida, Wooly Butterfly Bush
- Pink:
- Arizona Penstemon, Desert Willow,
Fairy Duster, Mexican Evening Primrose
- Red:
- Paintbrush, Red Yucca
- Varied:
- Climbing Milkweed (green, yellow, white, maroon), Lantana, Oleander
- White:
- American Carrot, Banana Yucca, Bear Grass, Cat-Claw Mimosa,
Desert-Chicory, Desert Tobacco, Elderberry, Fleabane, Odora,
Sego Lily, Tufted Globe Amaranth,
Western Soapberry, White Margin Spurge, White Nightshade,
White Prickly Poppy
- Yellow:
- Bahia, Broom Snakeweed, California Poppy,
Cat-Claw Acacia, Desert Dandelion,
Desert Marigold, Engelmann's Prickly Pear, Fiddleneck,
Gray Felt Thorn, Green's Lotus, Mormon Tea, Paperflower, Reddome Blanketflower,
San Felipe Dyssodia, Sundrops, Thick-leaved Ground Cherry (Ivyleaf Groundcherry),
Twin Leaf Senna, Velvet Mesquite,
Western Wallflower, Whitethorn Acacia,
Yellow Bird of Paradise, Yellow Columbine, Yellow Linanthus,
Yerba de Pasmo
Red berries of Three-Leaf Sumac are ready for harvest. Desert Ceanothus drops its dried
fruit by the end of the month. The most commonly seen wildflowers are Broom Snakeweed,
Dakota Verbena, Desert Marigold, Elderberry, Fleabane, Globemallow, Sida, Thistle and White Prickly Poppy.
At the end of the month, White Prickly Poppy is the most commonly visible wildflower.
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- June
-
In an average year, it will rain only one day in June, although no rain at all is common.
The Monsoon Season, however, has been officially defined as starting in the middle of June.
On years with wet summers,
precursor rains appear in the first three weeks of the month followed by monsoon rains in the fourth week.
Low temperatures are usually in the sixties and seventies with high temperatures in the high nineties.
Heat waves may occur on some days with lows in the seventies and highs in the one hundreds.
An occasional Pacific cold front will blow through, providing strong gusting winds with low temperatures
in the low fifties and highs in the low eighties.
Most days the wind will vary from none or mild to moderate speeds. On a few days sustained wind speeds
of 25-30 mph will last an entire day with wind gusts up to 45 mph.
Occasional strong gusts, lasting for a few minutes to hours, appear as often as half of the days of the month.
Plants in Bloom by Color
- Blue:
- Arizona Blue Eyes, Fountain Butterfly Bush, Miniature Wool Star,
Small Wirelettuce, Thurber's Stephanomeria
- Magenta / Purple:
- Cane Cholla, Filaree, Narrow Leaf Aster, New Mexico Thistle, Silverleaf Nightshade,
Tansyleaf Spine Aster, Trailing Four O'clock
- Orange:
- Copper Purslane, Engelmann's Prickly Pear, Globemallow,
Wooly Butterfly Bush
- Pink:
- Desert Willow, Fairy Duster,
Field Bindweed, Mexican Evening Primrose
- Red:
- Penstemon barbatus, Red Yucca
- Varied:
- Climbing Milkweed (green, yellow, white or maroon), Lantana, Oleander
- White:
- Bear Grass, Cat-Claw Mimosa, Desert Spoon, Elderberry, Fleabane,
Odora, Photinia, Sacred Datura, Saguaro Cactus, Soapweed Yucca,
Western Soapberry, White Prickly Poppy
- Yellow:
- Broom Snakeweed, Cat-Claw Acacia,
Chilean (Hybrid) Mesquite,
Desert Marigold, Engelmann's Prickly Pear,
Goldenflower Century Plant (Agave chrysantha), Palo Verde,
San Felipe Dyssodia, Sunflower, Thick-leaved Ground Cherry (Ivyleaf Groundcherry),
Thimblehead, Twin Leaf Senna,
Velvet Mesquite, Whitethorn Acacia,
Yellow Bird of Paradise, Yellow Columbine
Fruits of Manzanita (red), Rabbit Thorn (dark purple) and Three Leaf Sumac (red-brown) are ready
for harvest. Acorns of Emory Oak are starting to form.
Elderberry fruits ripen by the end of the month on those trees with sufficient water resources.
Tree of Heaven seed pod clusters are forming, turning colors of yellow, pink, and red, sometimes mistaken
for flowers. Canyon Grape vines are climbing over everything within reach.
Chigger and mosquito season starts with monsoon rains.
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- July
-
The month of July is usually humid and often quite variable, swinging from cool and rainy one day
to hot and sunny the next. The skies are often cloudy, reducing temperatures by as much as ten degrees.
Some years, heavy rains are frequent, nearly every day in some weeks. Other years see very little rain
until the fourth week of July in spite of clouds and humidity. A typical year, however, will see monsoon
rains start the first week.
The first three weeks of July are often very windy with occasional strong gusts but the wind
often tapers off toward the end of the month.
Low temperatures reach the high sixties to low seventies while daytime highs can be in the high eighties
to one hundreds.
Plants in Bloom by Color
- Blue:
- Arizona Blue Eyes, Small Wirelettuce,
Snapdragon Vine
- Green:
- Desert Pipevine (green and brown)
- Magenta / Purple:
- Dakota Verbena, Desert Four O'clock, Filaree, Narrowleaf Aster,
Silverleaf Nightshade, Tansyleaf Spine Aster, Texas Ranger
- Orange:
- Arizona Caltrop, Globemallow,
Sida, Trumpet Creeper Vine,
Woolly Butterfly Bush
- Pink:
- Desert Willow, Mexican Evening Primrose
- Red:
- Firewheel,
Red Bird of Paradise, Red Yucca,
Scarlet Penstemon, Snapdragon Vine
- Varied:
- Oleander
- White:
- Desert Spoon, Fleabane, Redwhisker Clammyweed, Sacred Datura,
Shrubby Buckwheat, Soapweed Yucca, White Margin Spurge,
White Prairie Clover, White Prickly Poppy
- Yellow:
- Buffalo-bur, Camphorweed, Deervetch, Desert Marigold,
Goldenflower Century Plant (Agave chrysantha), Slimpod Senna,
Sunflower, Thick-leaved Ground Cherry
(Ivyleaf Groundcherry), Thimblehead,
Twin Leaf Senna, Western Wallflower, Wright's Deervetch,
Yellow Bird of Paradise
Elderberry fruit is ripe at the start of the month. Ebony Oak acorns ripen and fall this month.
Berries of Hollyleaf Buckthorn are turning red.
Many of the flowers listed above will bloom in July only with abundant monsoon rains.
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- August
-
Rainfall in August varies considerably, ranging from nearly every day in some years to once a week
in others. Monsoon rains usually drop off toward the end of the month. Skies are often cloudy and
wind varies from almost none in some years to frequent strong winds in others.
Humidity varies with rainfall.
A few years will see 1/2 inch hailstones for a few minutes on one or two days.
Low temperatures are in the high sixties to low seventies. Daytime highs are in the nineties
but may vary from the low eighties with abundant rain to low one-hundreds when dry. August
is often the least windy month of the summer.
Plants in Bloom by Color
- Blue:
- Arizona Blue Eyes, Rosemary,
Scurf Pea, Small Wirelettuce,
Western Spiderwort, Woolly Morning Glory vine
- Green:
- Desert Pipevine, Fringed Amaranth, Spreading Sida
- Magenta / Purple:
- Dakota Verbena, Desert Four O'clock, Filaree, Purple Aster, Purple Nightshade,
Range Ratany, Ribbon Four O'clock, Texas Ranger
- Orange:
- Arizona Caltrop,
Copper Purslane, Desert Honeysuckle,
Globemallow,
Orange Flameflower, Sida
- Pink:
- Desert Willow, Fairy Duster,
Hoary Bindweed
- Red:
- Winged Purslane, Compass Barrel Cactus, Desert Paintbrush,
Firewheel, Scarlet Penstemon,
Red Spiderling
- Varied:
- Lantana, Oleander
- White:
- Catclaw Mimosa, Devil's Claw, Fern Acacia,
Fleabane, Odora, Redwhisker Clammyweed, Sacred Datura,
Shrubby Buckwheat,
White Margin Spurge, White Nightshade, White Prairie Clover, White Prickly Poppy,
White Sida, Wild Cotton
- Yellow:
- Abert's Dome, Broom Snakeweed, Camphorweed, Desert Marigold,
Five-Needle Fetid Marigold, Mesquite, Paperflower, Puncture Vine,
Slimpod Senna, Sunflower, Tacoma Stans, Thick-Leaved Ground Cherry,
Thimblehead, Tree Tobacco,
Twin Leaf Senna, Western Wallflower,
Whitethorn Acacia, Yellow Bird of Paradise.
Berries of Hollyleaf Buckthorn are turning red on late-blooming plants. Western Soapberry trees are
dropping their pale green-yellow fruit. Most elderberry trees have lost their leaves.
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- September
-
Rainfall in September drops off considerably from August, with rain perhaps four days of the month.
The monsoon season officially ends the last day of September although heavy rains seldom occur past
the first week.
Low temperatures vary from the high fifties to low seventies, mostly in the mid-sixties. Daytime highs are
in the eighties to nineties. Winds are variably mild to strong and gusty.
Plants in Bloom by Color
- Blue:
- Arizona Blue Eyes, Many-Flowered Gilia, Western Spiderwort, Woolly Morning Glory vine
- Magenta / Purple:
- Dakota Verbena, Desert Four O'clock,
Purple Aster, Range Ratany, Silver-Leaf Nightshade
- Orange:
- Arizona Caltrop, Copper Purslane,
Desert Globemallow, Sida
- Pink:
- Fairy Duster, Hoary Bindweed
- Red:
- Compass Barrel Cactus, Paintbrush, Red Spiderling,
Scarlet Creeper vine.
- White:
- Devil's Claw, Elderberry (when situated in a low, water-collecting area),
Fern Acacia, Fleabane,
Redwhisker Clammyweed, Sacred Datura,
Shrubby Buckwheat, Sweet Four O'clock, Virgin's Bower vine,
White Margin Spurge, White Nightshade, White Prickly Poppy.
- Yellow:
- Broom Snakeweed, Camphorweed, Cat-claw Acacia, Cudweed,
Desert Marigold, Golden Crownbeard,
Paper Flower, Puncture Vine, Sunflower, Thick-Leaved Ground Cherry,
Thimblehead, Twin Leaf Senna, Wright's Deervetch,
Yellow Bird of Paradise
Dakota Verbena (during heavy rainfall years),
Thimblehead and Sacred Datura
are the most widespread and persistent.
Grasshoppers have reached their peak this the month. Chigger infestations in tall grass are fading away
in the third week of September with the persistence of cooler weather.
The year's second brood of Pipevine Swallowtail caterpillars has been seen every week in September.
Spittlebug foam nests are being reported on Rosemary and other plants.
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- October
-
It often rains only one day in October. Years with very wet summers may see rain fall nearly half
of the days in the first two weeks, then disappear. Hail may also be present in very rainy years.
Low temperatures may start in the sixties but drop by the second week to the forties and fifties
depending on whether a Pacific cold front is pushing through.
Daytime highs are mostly in the seventies and eighties but can range from the sixties in cold years
to low nineties in warm ones. Many days of the month are very windy.
Plants in Bloom by Color
- Blue:
- Small Wirelettuce (Stephanomeria exigua),
Woolly Morning Glory
- Magenta / Purple:
- Dakota Verbena, Filaree,
Purple Aster
- Orange:
- Desert Globemallow, Sida
- Pink:
- Fairy Duster
- Varied:
- Lantana, Oleander
- White:
- Brickellia, Elderberry (when situated in a low, water-collecting area), Fleabane, Shrubby Buckwheat
- Yellow:
- Camphorweed, Cudweed, Desert Marigold, Sunflower,
Tecoma Stans, Thimblehead,
Turpentine Brush
The orange-red berries of Pyracantha make a colorful showing.
In high rainfall years elderberry trees have regained their leaves and are in their second bloom of the year.
In low rainfall years, the most reliable fall wildflowers are camphorweed, cudweed, sacred datura,
sunflower and thimblehead.
Seed pods of many wildflowers, including Scarlet Creeper, Fern Acacia, Slimpod Senna and Yellow Bird of
Paradise are ready to harvest for next year's seed crop.
Tall grass is green at the start of October although all seeds have dropped. By the end of the month grass
will dry out and die.
Grasshoppers are numerous at the start but most disappear by the end of the month.
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- November
-
Freezing temperatures of the fall season first appear in November. Temperatures for the month start
out moderate, and then drop abruptly into winter in the last two weeks. Lows are in the high forties and
fifties at the beginning and by the end are in the teens to fifties. Highs start in the seventies,
and then drop to the twenties in really cold years to the sixties in warm years. November is on average
the driest month of the year outside of May. Significant rain is rare to none.
Winds become calmer and less frequent toward the end of the month.
Plants in Bloom by Color
- Blue:
- Small Wirelettuce
- Magenta / Purple:
- Dakota Verbena, Filaree, Purple Aster
- Pink:
- Fairy Duster
- White:
- Fleabane, Sacred Datura
- Yellow:
- Camphorweed, Desert Marigold, Sunflower (in protected locations)
Desert Broom plants begin dispersing white fluffy seeds.
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- December
-
Low temperatures range from the twenties to forties. High temperatures range between the forties and
sixties. The month may be very dry, with one light rain sprinkle, or wet, with heavy rains on
several days. Snow, if it occurs, can first appear for the fall and winter season in December.
The first week of December may bring fog and heavy rain or continue a fall drought. Hard freezes
are common. Strong winds, from Pacific storms, can bring plunging temperatures. The north face of
Mount Lemmon will sometimes be covered with snow.
Plants in Bloom by Color
- Blue:
- Small Wirelettuce and Toadflax in years with wet summers
- Magenta / Purple:
- Filaree in years with wet summers
- White:
- Fleabane in years with wet summers
- Yellow:
- Annual Goldeneye (may appear after rain), Camphorweed
In December, the leaves of Western Cottonwood and Tree of Heaven turn yellow and drop.
Elderberry trees, with a prolonged fall drought, will lose their leaves for the second time in the year.
The leaves on Catclaw Mimosa (Wait-A-Minute Bush) turn brown and drop by the end of December.
The leaves of Catclaw Acacia and Velvet Mesquite do not turn brown, but thin out,
dropping when they are still pale green until none are left.
Desert Broom plants display their white fluffy seeds through the end of the month.
The best looking plant this time of year is Pyracantha which has glossy green leaves and heavy clusters
of orange berries.
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