Arco, ID climate
Arco has cold winters and warm summers, with very little rain. A typical July afternoon reaches 86°, a January night drops to 7°, and about 24 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Arco feels like
Winter
Spring
Summer
Fall
Arco 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 | 30-yr range |
|---|---|---|---|---|---|---|
| January | 29° | 7° | 0.8" | 7.0" | 4 | 9° – 26° |
| February | 34° | 11° | 0.7" | 4.6" | 4 | 14° – 34° |
| March | 45° | 22° | 0.7" | 1.1" | 4 | 25° – 41° |
| April | 55° | 29° | 0.9" | 1.3" | 5 | 36° – 47° |
| May | 65° | 38° | 1.3" | 0.2" | 6 | 46° – 58° |
| June | 75° | 44° | 1.0" | 0 | 4 | 54° – 66° |
| July | 86° | 51° | 0.4" | 0 | 2 | 58° – 74° |
| August | 84° | 49° | 0.5" | 0 | 3 | 60° – 70° |
| September | 73° | 40° | 0.7" | 0 | 4 | 52° – 62° |
| October | 58° | 29° | 0.8" | 0.3" | 4 | 34° – 50° |
| November | 41° | 18° | 0.6" | 1.2" | 3 | 22° – 36° |
| December | 30° | 8° | 0.9" | 8.1" | 5 | 11° – 25° |
| Year | 56° | 29° | 9.3" | 23.8" | 48 |
“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 Arco
Arco gets 9 inches of rain and melted snow a year. May is the wettest month and July the driest. Rain or snow falls on about 48 days a year.
About 119 frost-free days a year
In half of years the last 32° night comes by May 22 and the first one by September 22. That leaves about 119 frost-free days for gardens, shorter than 97% of U.S. towns.
Heating and cooling a home in Arco
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Arco, 96% of that work is heating and 4% 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 Arco 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 Arco averaged 1.1° warmer than the 1900s. The biggest change is in March (+2.8°). The shift is smaller than in 58% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Arco’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 14° to 34°. September is the most reliable, staying within 9°.
Common questions about Arco’s climate
What is the coldest month in Arco?
January, with a typical high of 29° and a low of 7°.
What is the hottest month in Arco?
July, with a typical high of 86° and a low of 51°. About 19 days a year reach 90°.
How much snow does Arco get?
About 24 inches in a normal winter, most of it in December.
When is the first frost in Arco?
In half of years the first 32° night comes by September 22, and the last spring frost by May 22.
What is the rainiest month in Arco?
May, with 1.3 inches of rain and melted snow. The year totals 9 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Arco itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Arco, ID (1 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.