Climateby Month

Boise vs Sun Valley weather

Boise, ID and Sun Valley, ID · 93 mi apart

July highs: 93°F in Boise, 80°F in Sun Valley (Boise is 13°F warmer). January highs: 39°F and 31°F (Boise is 8°F warmer). Boise has about 89 wet days a year, Sun Valley about 84. Snow: 17.6 in a year in Boise, 102.0 in in Sun Valley.

Boise, ID

0°20°40°60°80°100° January: normal high 39°F (4°C), low 26°F (-3°C) 39° 26° February: normal high 46°F (8°C), low 29°F (-2°C) March: normal high 56°F (13°C), low 35°F (2°C) April: normal high 62°F (17°C), low 40°F (4°C) May: normal high 72°F (22°C), low 48°F (9°C) June: normal high 81°F (27°C), low 54°F (12°C) July: normal high 93°F (34°C), low 62°F (17°C) 93° 62° August: normal high 91°F (33°C), low 61°F (16°C) September: normal high 80°F (27°C), low 53°F (12°C) October: normal high 65°F (18°C), low 42°F (6°C) November: normal high 49°F (9°C), low 32°F (0°C) December: normal high 39°F (4°C), low 25°F (-4°C) JFMAMJJASOND

Best months: May

Sun Valley, ID

0°20°40°60°80°100° January: normal high 31°F (-1°C), low 8°F (-13°C) February: normal high 35°F (2°C), low 11°F (-12°C) March: normal high 43°F (6°C), low 19°F (-7°C) April: normal high 52°F (11°C), low 27°F (-3°C) May: normal high 62°F (17°C), low 35°F (2°C) June: normal high 70°F (21°C), low 40°F (4°C) July: normal high 80°F (27°C), low 45°F (7°C) 80° 45° August: normal high 79°F (26°C), low 44°F (7°C) September: normal high 69°F (21°C), low 36°F (2°C) October: normal high 56°F (13°C), low 28°F (-2°C) November: normal high 41°F (5°C), low 17°F (-8°C) December: normal high 30°F (-1°C), low 9°F (-13°C) 30° 9° JFMAMJJASOND

Best months: June

Which city for what

  • Milder winters: Boise (January high 39°F vs January high 31°F)
  • Cooler summers: Sun Valley (July high 80°F vs July high 93°F)
  • Less snow: Boise (17.6 in vs 102.0 in)
  • Longer growing season: Boise (179 frost-free days vs 139 frost-free days)

Listed only where the difference is at least 3°F in highs, 10 days a year or 3 in of snow.

Season by season

SeasonAvg high BoiseAvg high Sun ValleyWet days BoiseWet days Sun Valley
Winter (Dec-Feb)41°F32°F3229
Spring (Mar-May)63°F52°F2823
Summer (Jun-Aug)88°F76°F1016
Fall (Sep-Nov)65°F55°F2016

Side by side over a year

BoiseSun Valley
Hot days (90°F+)553
Freezing nights108229
Muggy days00
Comfortable days75–
Precipitation11.5 in17.3 in
Snowfall17.6 in102.0 in
Frost dateslast Apr 24, first Oct 21last May 13, first Oct 2
Daylight in June / December15.4 h / 9.0 h15.4 h / 9.0 h
Best monthsMayJune

Day counts from each city's daily records, 1991-2020. Comfortable days: highs 65-80°F and dew point under 60°F.

Month by month

MonthHigh BoiseHigh Sun ValleyWet days BoiseWet days Sun Valley
January39°F31°F1110
February46°F35°F99
March56°F43°F108
April62°F52°F97
May72°F62°F88
June81°F70°F58
July93°F80°F24
August91°F79°F24
September80°F69°F44
October65°F56°F65
November49°F41°F106
December39°F30°F1211

Both charts use the same temperature scale.

Where the numbers come from

  • Boise, ID: temperature from Boise Air Terminal (USW00024131), 3.7 mi SSW of the city center; precipitation from Boise Air Terminal (USW00024131). NOAA 1991-2020 normals and daily records.
  • Sun Valley, ID: temperature from Ketchum RS (USC00104845), 1.0 mi SSW of the city center; precipitation from Ketchum RS (USC00104845). NOAA 1991-2020 normals and daily records.

Every station for each city, including humidity and frost, is listed on the city page. Methodology.