Idaho climate by month
January highs across Idaho range from 31°F in Sun Valley to 39°F in Boise; July highs from 80°F in Sun Valley to 93°F in Boise. The most common best months across these cities are May, June.
Idaho weather month by month
Average of the 2 Idaho cities on this site, computed from NOAA's unrounded values (so it can differ by a degree from averaging the rounded city figures); individual cities differ, sometimes a lot.
| Month | High | Low | Wet days | Snow |
|---|---|---|---|---|
| January | 35°F | 17°F | 10 | 16.1 in |
| February | 41°F | 20°F | 9 | 10.3 in |
| March | 49°F | 27°F | 9 | 5.8 in |
| April | 57°F | 33°F | 8 | 1.7 in |
| May | 67°F | 41°F | 8 | 0.1 in |
| June | 76°F | 47°F | 7 | 0.0 in |
| July | 86°F | 54°F | 3 | 0.0 in |
| August | 85°F | 52°F | 3 | 0.0 in |
| September | 75°F | 44°F | 4 | 0.0 in |
| October | 60°F | 35°F | 6 | 0.9 in |
| November | 45°F | 25°F | 8 | 6.2 in |
| December | 35°F | 17°F | 11 | 18.8 in |
Regional differences
- Warmest winterBoise: January high 39°F
- Coolest summerSun Valley: July high 80°F
- Most wet daysBoise: 89 a year
- Fewest wet daysSun Valley: 84 a year
- Most snowSun Valley: 102.0 in a year
Warmest and coolest Idaho city each month
| Month | Warmest | Coolest | Best month for |
|---|---|---|---|
| January | Boise 39°F | Sun Valley 31°F | – |
| February | Boise 46°F | Sun Valley 35°F | – |
| March | Boise 56°F | Sun Valley 43°F | – |
| April | Boise 62°F | Sun Valley 52°F | – |
| May | Boise 72°F | Sun Valley 62°F | 1 city |
| June | Boise 81°F | Sun Valley 70°F | 1 city |
| July | Boise 93°F | Sun Valley 80°F | – |
| August | Boise 91°F | Sun Valley 79°F | – |
| September | Boise 80°F | Sun Valley 69°F | – |
| October | Boise 65°F | Sun Valley 56°F | – |
| November | Boise 49°F | Sun Valley 41°F | – |
| December | Boise 39°F | Sun Valley 30°F | – |
By normal daily high. "Best month for": how many of the 2 cities have it among their best months by our comfort score.
Frost and humidity across Idaho
- Earliest typical last frostBoise: Apr 24
- Latest typical last frostSun Valley: May 13
- Most muggy daysBoise: 0 a year
- Fewest muggy daysSun Valley: 0 a year
All Idaho cities
| City | Jan high | Jul high | Wet days/yr | Snow/yr | Best months |
|---|---|---|---|---|---|
| Boise | 39°F | 93°F | 89 | 17.6 in | May |
| Sun Valley | 31°F | 80°F | 84 | 102.0 in | Jun |
Also covered: Meridian (see Boise), Nampa (see Boise). These cities use the same weather stations as the city named.