Flagstaff, AZ climate
Flagstaff has chilly, snowy winters and pleasant summers, with very little rain. A typical July afternoon reaches 84°, a January night drops to 16°, and about 90 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Flagstaff feels like
Winter
Spring
Summer
Fall
Flagstaff weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 45° | 16° | 1.8" | 20.9" | 7 | 20 | 24° – 37° |
| February | 48° | 18° | 1.8" | 19.3" | 8 | 14 | 28° – 40° |
| March | 54° | 23° | 1.6" | 15.6" | 7 | 7 | 32° – 44° |
| April | 61° | 27° | 0.8" | 5.0" | 5 | 1 | 38° – 49° |
| May | 70° | 34° | 0.7" | 1.1" | 5 | 0 | 46° – 56° |
| June | 81° | 41° | 0.3" | 0 | 2 | 0 | 56° – 65° |
| July | 84° | 50° | 2.5" | 0 | 12 | 0 | 64° – 70° |
| August | 81° | 49° | 3.1" | 0 | 13 | 0 | 62° – 69° |
| September | 76° | 41° | 1.7" | 0 | 8 | 0 | 55° – 61° |
| October | 65° | 30° | 1.2" | 1.5" | 5 | 0 | 44° – 53° |
| November | 54° | 22° | 1.2" | 8.2" | 4 | 4 | 30° – 45° |
| December | 45° | 15° | 1.5" | 18.5" | 7 | 16 | 24° – 35° |
| Year | 64° | 30° | 18.1" | 90.1" | 82 | 62 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in Flagstaff
Flagstaff gets 18 inches of rain and melted snow a year. August is the wettest month and June the driest. Rain or snow falls on about 82 days a year. Snow covers the ground about 62 days of the year.
About 115 frost-free days a year
In half of years the last 32° night comes by June 4 and the first one by September 28. That leaves about 115 frost-free days for gardens, shorter than 98% of U.S. towns.
Heating and cooling a home in Flagstaff
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Flagstaff, 98% of that work is heating and 2% is cooling, so the furnace matters far more than the air conditioner.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
Flagstaff and its neighbors
Flagstaff borders 2 towns with climate data. January nights across them vary by 2.7°. Fort Valley has the coldest January nights (15°) and Doney Park the hottest July afternoons (86°). Flagstaff’s January low is 16° and its July high 84°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Flagstaff compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in Flagstaff averaged 1.8° warmer than the 1900s. The biggest change is in March (+3.3°). The shift is larger than in 89% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Flagstaff’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. November swings the most: between 1991 and 2020 its average temperature ranged from 30° to 45°. September is the most reliable, staying within 6°.
Common questions about Flagstaff’s climate
What is the coldest month in Flagstaff?
December, with a typical high of 45° and a low of 15°.
What is the hottest month in Flagstaff?
July, with a typical high of 84° and a low of 50°. About 3 days a year reach 90°.
How much snow does Flagstaff get?
About 90 inches in a normal winter, most of it in January.
When is the first frost in Flagstaff?
In half of years the first 32° night comes by September 28, and the last spring frost by June 4.
What is the rainiest month in Flagstaff?
August, with 3.1 inches of rain and melted snow. The year totals 18 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Flagstaff itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Flagstaff Pulliam Airport, AZ (4 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.