Portola, CA climate
Portola has chilly, snowy winters and warm summers. A typical July afternoon reaches 86°, a January night drops to 22°, and about 38 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Portola feels like
Winter
Spring
Summer
Fall
Portola 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 | 43° | 22° | 4.2" | 11.7" | 9 | 9 | 23° – 39° |
| February | 47° | 24° | 3.8" | 7.6" | 9 | 6 | 29° – 43° |
| March | 52° | 27° | 3.5" | 6.4" | 8 | 5 | 32° – 46° |
| April | 58° | 31° | 1.7" | 1.8" | 6 | 1 | 39° – 49° |
| May | 67° | 37° | 1.3" | 0.2" | 6 | 0 | 44° – 58° |
| June | 77° | 42° | 0.6" | 0 | 3 | 0 | 55° – 65° |
| July | 86° | 48° | 0.2" | 0 | 1 | 0 | 62° – 72° |
| August | 85° | 45° | 0.2" | 0 | 1 | 0 | 62° – 69° |
| September | 79° | 40° | 0.4" | 0.1" | 2 | 0 | 56° – 63° |
| October | 66° | 32° | 1.2" | 0.4" | 4 | 0 | 45° – 53° |
| November | 52° | 26° | 2.1" | 2.4" | 6 | 1 | 30° – 44° |
| December | 42° | 22° | 4.3" | 7.2" | 8 | 6 | 26° – 37° |
| Year | 63° | 33° | 23.5" | 37.8" | 62 | 29 |
“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 Portola
Portola gets 23 inches of rain and melted snow a year. December is the wettest month and August the driest. Rain or snow falls on about 62 days a year. Snow covers the ground about 29 days of the year.
About 91 frost-free days a year
In half of years the last 32° night comes by June 11 and the first one by September 10. That leaves about 91 frost-free days for gardens, shorter than 99% of U.S. towns.
Heating and cooling a home in Portola
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Portola, 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.
Portola and its neighbors
Portola borders 3 towns with climate data. January nights across them vary by 1.3°. Delleker has both the coldest January nights (22°) and the hottest July afternoons (86°). Portola’s January low is 22° and its July high 86°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Portola 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 Portola averaged 1.4° warmer than the 1900s. The biggest change is in January (+2.4°). The shift is larger than in 64% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Portola’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. January swings the most: between 1991 and 2020 its average temperature ranged from 23° to 39°. August is the most reliable, staying within 7°.
Common questions about Portola’s climate
What is the coldest month in Portola?
December, with a typical high of 42° and a low of 22°.
What is the hottest month in Portola?
July, with a typical high of 86° and a low of 48°. About 22 days a year reach 90°.
How much snow does Portola get?
About 38 inches in a normal winter, most of it in January.
When is the first frost in Portola?
In half of years the first 32° night comes by September 10, and the last spring frost by June 11.
What is the rainiest month in Portola?
December, with 4.3 inches of rain and melted snow. The year totals 23 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Portola itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Portola, CA (1 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.