Lewiston, CA climate
Lewiston has mild winters and hot summers. A typical July afternoon reaches 94°, a January night drops to 34°, and about 6 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Lewiston feels like
Winter
Spring
Summer
Fall
Lewiston 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 | 50° | 34° | 7.8" | 1.2" | 15 | 0 | 37° – 47° |
| February | 55° | 35° | 7.6" | 1.6" | 12 | 0 | 39° – 51° |
| March | 60° | 37° | 6.8" | 0.3" | 13 | 0 | 41° – 55° |
| April | 66° | 40° | 3.4" | 0 | 10 | 0 | 48° – 58° |
| May | 76° | 46° | 2.0" | 0 | 8 | 0 | 53° – 68° |
| June | 85° | 52° | 0.9" | 0 | 3 | 0 | 63° – 76° |
| July | 94° | 59° | 0.1" | 0 | 1 | 0 | 71° – 80° |
| August | 93° | 57° | 0.2" | 0 | 1 | 0 | 72° – 80° |
| September | 88° | 51° | 0.4" | 0 | 2 | 0 | 66° – 74° |
| October | 74° | 44° | 2.5" | 0 | 5 | 0 | 55° – 64° |
| November | 57° | 38° | 5.1" | 0.6" | 11 | 0 | 39° – 53° |
| December | 48° | 34° | 8.9" | 2.7" | 15 | 1 | 38° – 46° |
| Year | 70° | 44° | 45.6" | 6.4" | 95 | 1 |
“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 Lewiston
Lewiston gets 46 inches of rain and melted snow a year. December is the wettest month and July the driest. Rain or snow falls on about 95 days a year.
About 178 frost-free days a year
In half of years the last 32° night comes by April 23 and the first one by October 22. That leaves about 178 frost-free days for gardens, longer than 50% of U.S. towns.
Heating and cooling a home in Lewiston
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Lewiston, 83% of that work is heating and 17% 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.
How Lewiston 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 Lewiston averaged 1.5° warmer than the 1900s. The biggest change is in September (+2.3°). The shift is larger than in 71% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Lewiston’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. May swings the most: between 1991 and 2020 its average temperature ranged from 53° to 68°. September is the most reliable, staying within 7°.
Common questions about Lewiston’s climate
What is the coldest month in Lewiston?
December, with a typical high of 48° and a low of 34°.
What is the hottest month in Lewiston?
July, with a typical high of 94° and a low of 59°. About 78 days a year reach 90°.
How much snow does Lewiston get?
About 6 inches in a normal winter, most of it in December.
When is the first frost in Lewiston?
In half of years the first 32° night comes by October 22, and the last spring frost by April 23.
What is the rainiest month in Lewiston?
December, with 8.9 inches of rain and melted snow. The year totals 46 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Lewiston itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Trinity Rvr Hatchery, CA (2 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.