Sweetwater, ID climate
Sweetwater has mild winters and warm summers, with very little rain. A typical July afternoon reaches 90°, a January night drops to 28°, and about 13 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Sweetwater feels like
Winter
Spring
Summer
Fall
Sweetwater 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 | 41° | 28° | 1.5" | 2.7" | 11 | 3 | 25° – 40° |
| February | 46° | 29° | 1.3" | 3.8" | 10 | 3 | 29° – 45° |
| March | 55° | 33° | 2.0" | 0.8" | 12 | 1 | 38° – 50° |
| April | 62° | 38° | 2.0" | 0 | 11 | 0 | 45° – 56° |
| May | 72° | 45° | 2.3" | 0 | 11 | 0 | 53° – 63° |
| June | 78° | 50° | 1.8" | 0 | 9 | 0 | 60° – 71° |
| July | 90° | 56° | 0.6" | 0 | 4 | 0 | 63° – 77° |
| August | 90° | 55° | 0.5" | 0 | 3 | 0 | 67° – 75° |
| September | 80° | 47° | 0.8" | 0 | 5 | 0 | 60° – 68° |
| October | 63° | 39° | 1.5" | 0 | 9 | 0 | 46° – 58° |
| November | 48° | 33° | 1.9" | 1.3" | 11 | 1 | 33° – 46° |
| December | 39° | 28° | 1.7" | 4.1" | 11 | 3 | 27° – 38° |
| Year | 64° | 40° | 17.9" | 12.7" | 106 | 11 |
“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 Sweetwater
Sweetwater gets 18 inches of rain and melted snow a year. May is the wettest month and August the driest. Rain or snow falls on about 106 days a year. Snow covers the ground about 11 days of the year.
About 200 frost-free days a year
In half of years the last 32° night comes by April 6 and the first one by October 26. That leaves about 200 frost-free days for gardens, longer than 72% of U.S. towns.
Heating and cooling a home in Sweetwater
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Sweetwater, 85% of that work is heating and 15% 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 Sweetwater 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 Sweetwater averaged 1.3° warmer than the 1900s. The biggest change is in January (+3.7°). The shift is larger than in 54% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Sweetwater’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. February swings the most: between 1991 and 2020 its average temperature ranged from 29° to 45°. August is the most reliable, staying within 7°.
Common questions about Sweetwater’s climate
What is the coldest month in Sweetwater?
December, with a typical high of 39° and a low of 28°.
What is the hottest month in Sweetwater?
August, with a typical high of 90° and a low of 55°. About 44 days a year reach 90°.
How much snow does Sweetwater get?
About 13 inches in a normal winter, most of it in December.
When is the first frost in Sweetwater?
In half of years the first 32° night comes by October 26, and the last spring frost by April 6.
What is the rainiest month in Sweetwater?
May, with 2.3 inches of rain and melted snow. The year totals 18 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Sweetwater itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Lewiston Nez Perce Co Airport, ID (10 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.