Climate averages 1991–2020
Flagstaff weather
by month.
See how the year changes. July has the highest average daily maximum; June has the lowest average monthly rainfall.
Pleasant-weather months by our simple rule: MayJune
Long-term climate patterns, not a forecast for a particular trip.
Across the year Flagstaff averages a daytime high of 16.5°C and a nighttime low of 5.4°C, with about 625 mm of rain on roughly 90 days. July is the warmest month (average high 27.9°C) and January (tied with December) the coolest (5.7°C). August is the wettest month with 126 mm; June is the driest with 11 mm.
Months with pleasant weather by a simple rule (average high between 18°C and 29°C, average low of at least 5°C and at most 8 rain days): May and June. This looks at temperature and rain only, not humidity, wind, sea temperature or crowds.
The annual picture
A year in Flagstaff
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Flagstaff climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 5.7°C-3.8°C | -3.8°C | 47 | 6.3 | 10.110 h |
| February | 7.0°C-3.0°C | -3.0°C | 50 | 6.9 | 10.911 h |
| March | 10.7°C-0.3°C | -0.3°C | 49 | 7.3 | 11.912 h |
| April | 15.0°C2.8°C | 2.8°C | 31 | 5.6 | 13.113 h |
| May | 20.5°C7.7°C | 7.7°C | 32 | 5.7 | 14.014 h |
| June | 26.8°C13.2°C | 13.2°C | 11 | 3.0 | 14.514 h |
| July | 27.9°C15.9°C | 15.9°C | 115 | 14.7 | 14.314 h |
| August | 26.2°C15.2°C | 15.2°C | 126 | 16.3 | 13.513 h |
| September | 23.3°C12.4°C | 12.4°C | 57 | 8.8 | 12.412 h |
| October | 17.7°C6.9°C | 6.9°C | 33 | 5.2 | 11.311 h |
| November | 11.2°C1.0°C | 1.0°C | 32 | 4.1 | 10.410 h |
| December | 5.7°C-3.6°C | -3.6°C | 41 | 5.8 | 9.810 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
Nearby cities
- SurpriseUnited States · 185 kmHigh 29.4°C · Low 15.7°C · 247 mm rain a year
- Peoria (Arizona), United StatesUnited States · 188 kmHigh 29.4°C · Low 15.6°C · 221 mm rain a year
- ScottsdaleUnited States · 189 kmHigh 29.3°C · Low 15.2°C · 248 mm rain a year
- Glendale (Arizona), United StatesUnited States · 191 kmHigh 29.6°C · Low 15.6°C · 221 mm rain a year
- MesaUnited States · 198 kmHigh 29.5°C · Low 14.8°C · 270 mm rain a year
- PhoenixUnited States · 198 kmHigh 29.7°C · Low 15.4°C · 248 mm rain a year
- TempeUnited States · 200 kmHigh 29.6°C · Low 15.2°C · 248 mm rain a year
- AvondaleUnited States · 206 kmHigh 30.1°C · Low 16.0°C · 221 mm rain a year
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsWhat do the high and low temperatures mean?
We average the daily maximum and daily minimum for each calendar month over 1991–2020. They are not record extremes, a forecast range or temperatures at a fixed time of day.
How is a rain day counted?
A local calendar day (standard time, UTC-7, no daylight saving) with at least 1 mm of total precipitation counts as one rain day. We count these for each year and month, then average across 30 years. The average does not predict which days will be wet.
Where do the numbers come from?
ERA5-Land (temperature) and ERA5 (precipitation) reanalysis from the Copernicus Climate Change Service, read from the Open-Meteo open-data archive. Temperature comes from the 0.1° model cell at 35.20°, -111.70° (4 km from the city centre), adjusted up by 1.0°C for the difference between the city's elevation (2,108 m) and the cell's (2,265 m). Rain comes from the 0.25° cell at 35.25°, -111.75°. These are model estimates, not weather-station readings; coast, hills and city streets can differ.
Does this page show sunshine, humidity or sea temperature?
No. The data used here contain air temperature and precipitation only. Daylight hours are calculated from the city's latitude (sunrise to sunset), not measured sunshine.