Index, WA climate
Index has mild, snowy winters and cool summers, with plenty of rain. A typical July afternoon reaches 74°, a January night drops to 32°, and about 44 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Index feels like
Winter
Spring
Summer
Fall
Index 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 | 42° | 32° | 14.2" | 13.8" | 20 | 16 | 32° – 43° |
| February | 46° | 32° | 9.7" | 4.6" | 17 | 9 | 31° – 45° |
| March | 51° | 34° | 10.6" | 3.8" | 20 | 3 | 37° – 48° |
| April | 56° | 37° | 7.8" | 0.8" | 18 | 0 | 41° – 53° |
| May | 64° | 43° | 5.3" | 0 | 15 | 0 | 49° – 57° |
| June | 68° | 47° | 4.1" | 0 | 13 | 0 | 54° – 63° |
| July | 74° | 51° | 1.8" | 0 | 7 | 0 | 58° – 67° |
| August | 75° | 52° | 2.0" | 0 | 6 | 0 | 59° – 68° |
| September | 69° | 47° | 4.5" | 0 | 11 | 0 | 54° – 61° |
| October | 58° | 41° | 10.4" | 0.1" | 17 | 0 | 46° – 54° |
| November | 47° | 36° | 15.2" | 4.2" | 20 | 3 | 35° – 46° |
| December | 41° | 32° | 13.5" | 17.0" | 20 | 12 | 32° – 40° |
| Year | 58° | 40° | 99.0" | 44.3" | 184 | 43 |
“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 Index
Index gets 99 inches of rain and melted snow a year. November is the wettest month and July the driest. Rain or snow falls on about 184 days a year. Snow covers the ground about 43 days of the year.
About 197 frost-free days a year
In half of years the last 32° night comes by April 14 and the first one by October 29. That leaves about 197 frost-free days for gardens, longer than 70% of U.S. towns.
Heating and cooling a home in Index
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Index, 97% of that work is heating and 3% 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 Index 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 Index averaged 1.0° warmer than the 1900s. The biggest change is in January (+3.3°). The shift is smaller than in 67% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Index’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 31° to 45°. September is the most reliable, staying within 7°.
Common questions about Index’s climate
What is the coldest month in Index?
February, with a typical high of 46° and a low of 32°.
What is the hottest month in Index?
August, with a typical high of 75° and a low of 52°. About 5 days a year reach 90°.
How much snow does Index get?
About 44 inches in a normal winter, most of it in December.
When is the first frost in Index?
In half of years the first 32° night comes by October 29, and the last spring frost by April 14.
What is the rainiest month in Index?
November, with 15.2 inches of rain and melted snow. The year totals 99 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Index itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Baring, WA (5 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.