Climateby Month

Portland vs Boise weather

Portland, OR and Boise, ID · 345 mi apart

July highs: 80°F in Portland, 93°F in Boise (Boise is 13°F warmer). January highs: 47°F and 39°F (Portland is 8°F warmer). Portland has about 156 wet days a year, Boise about 89. Snow: 4.2 in a year in Portland, 17.6 in in Boise.

Portland, OR

20°40°60°80°100° January: normal high 47°F (8°C), low 37°F (3°C) February: normal high 51°F (11°C), low 39°F (4°C) March: normal high 56°F (13°C), low 41°F (5°C) April: normal high 61°F (16°C), low 44°F (7°C) May: normal high 68°F (20°C), low 49°F (9°C) June: normal high 73°F (23°C), low 53°F (12°C) July: normal high 80°F (27°C), low 58°F (14°C) August: normal high 81°F (27°C), low 59°F (15°C) 81° 59° September: normal high 75°F (24°C), low 55°F (13°C) October: normal high 63°F (17°C), low 48°F (9°C) November: normal high 52°F (11°C), low 42°F (6°C) December: normal high 46°F (8°C), low 37°F (3°C) 46° 37° JFMAMJJASOND

Best months: June

Boise, ID

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

Which city for what

  • Milder winters: Portland (January high 47°F vs January high 39°F)
  • Cooler summers: Portland (July high 80°F vs July high 93°F)
  • Fewer wet days: Boise (89 a year vs 156 a year)
  • Less snow: Portland (4.2 in vs 17.6 in)
  • Longer growing season: Portland (247 frost-free days vs 179 frost-free days)
  • More comfortable days: Portland (104 a year vs 75 a year)

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 PortlandAvg high BoiseWet days PortlandWet days Boise
Winter (Dec-Feb)48°F41°F5332
Spring (Mar-May)62°F63°F4828
Summer (Jun-Aug)78°F88°F1610
Fall (Sep-Nov)63°F65°F3820

Side by side over a year

PortlandBoise
Hot days (90°F+)1255
Freezing nights18108
Muggy days00
Comfortable days10475
Precipitation36.9 in11.5 in
Snowfall4.2 in17.6 in
Frost dateslast Mar 13, first Nov 19last Apr 24, first Oct 21
Daylight in June / December15.6 h / 8.8 h15.4 h / 9.0 h
Best monthsJuneMay

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 PortlandHigh BoiseWet days PortlandWet days Boise
January47°F39°F1911
February51°F46°F169
March56°F56°F1810
April61°F62°F179
May68°F72°F138
June73°F81°F95
July80°F93°F42
August81°F91°F42
September75°F80°F74
October63°F65°F146
November52°F49°F1810
December46°F39°F1912

Both charts use the same temperature scale.

Where the numbers come from

  • Portland, OR: temperature from Portland Kgw-Tv (USC00356749), 0.7 mi WSW of the city center; precipitation from Portland Intl Airport (USW00024229). NOAA 1991-2020 normals and daily records.
  • 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.

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