Seneca, OR climate
Seneca has chilly winters and pleasant summers, with very little rain. A typical July afternoon reaches 83°, a January night drops to 16°.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Seneca feels like
Winter
Spring
Summer
Fall
Seneca weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | 30-yr range |
|---|---|---|---|---|
| January | 37° | 16° | 1.8" | 19° – 33° |
| February | 41° | 19° | 1.3" | 23° – 38° |
| March | 47° | 23° | 1.5" | 31° – 41° |
| April | 53° | 27° | 1.4" | 35° – 46° |
| May | 62° | 34° | 2.0" | 43° – 53° |
| June | 71° | 39° | 1.2" | 50° – 61° |
| July | 83° | 43° | 0.5" | 52° – 68° |
| August | 82° | 41° | 0.4" | 57° – 65° |
| September | 73° | 34° | 0.6" | 50° – 58° |
| October | 59° | 27° | 1.2" | 37° – 49° |
| November | 44° | 22° | 1.6" | 25° – 38° |
| December | 36° | 16° | 2.0" | 20° – 30° |
| Year | 57° | 28° | 15.4" |
“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 Seneca
Seneca gets 15 inches of rain and melted snow a year. December is the wettest month and August the driest.
A year-round growing season
Heating and cooling a home in Seneca
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Seneca, 100% of that work is heating and 0% 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 Seneca 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 Seneca averaged 1.3° warmer than the 1900s. The biggest change is in January (+3.7°). The shift is larger than in 55% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Seneca’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. July swings the most: between 1991 and 2020 its average temperature ranged from 52° to 68°. September is the most reliable, staying within 8°.
Common questions about Seneca’s climate
What is the coldest month in Seneca?
December, with a typical high of 36° and a low of 16°.
What is the hottest month in Seneca?
July, with a typical high of 83° and a low of 43°. About 13 days a year reach 90°.
When is the first frost in Seneca?
Frost is uncommon. Only 100% of years see a night at 32° or below.
What is the rainiest month in Seneca?
December, with 2.0 inches of rain and melted snow. The year totals 15 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Seneca itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Seneca, OR (1 mi, frost, heat and degree days). Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.