Castlewood, SD climate
Castlewood has cold, snowy winters and pleasant summers. A typical July afternoon reaches 82°, a January night drops to 3°, and about 41 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Castlewood feels like
Winter
Spring
Summer
Fall
Castlewood 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 | 22° | 3° | 0.6" | 6.7" | 6 | 26 | 0° – 25° |
| February | 26° | 7° | 0.6" | 8.9" | 6 | 21 | 3° – 28° |
| March | 39° | 19° | 1.2" | 5.4" | 7 | 15 | 19° – 44° |
| April | 54° | 31° | 2.3" | 5.2" | 9 | 4 | 33° – 51° |
| May | 67° | 44° | 3.2" | 0.1" | 11 | 0 | 51° – 62° |
| June | 77° | 55° | 4.1" | 0 | 11 | 0 | 60° – 70° |
| July | 82° | 59° | 3.5" | 0 | 10 | 0 | 62° – 77° |
| August | 79° | 56° | 3.2" | 0 | 9 | 0 | 62° – 72° |
| September | 72° | 47° | 2.7" | 0 | 9 | 0 | 53° – 64° |
| October | 57° | 34° | 2.1" | 1.4" | 8 | 1 | 38° – 50° |
| November | 40° | 20° | 0.9" | 4.5" | 5 | 5 | 19° – 41° |
| December | 27° | 9° | 0.7" | 8.9" | 6 | 22 | 4° – 25° |
| Year | 53° | 32° | 25.0" | 41.1" | 96 | 93 |
“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 Castlewood
Castlewood gets 25 inches of rain and melted snow a year. June is the wettest month and January the driest. Rain or snow falls on about 96 days a year. Snow covers the ground about 93 days of the year.
About 145 frost-free days a year
In half of years the last 32° night comes by May 6 and the first one by October 1. That leaves about 145 frost-free days for gardens, shorter than 85% of U.S. towns.
Heating and cooling a home in Castlewood
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Castlewood, 95% of that work is heating and 5% 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.
Castlewood and its neighbors
Castlewood borders 5 towns with climate data. January nights across them vary by 0.6°. Sheridan has the coldest January nights (2°) and Castlewood the hottest July afternoons (82°). Castlewood’s January low is 3° and its July high 82°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Castlewood 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 Castlewood averaged 1.2° warmer than the 1900s. The biggest change is in December (+3.2°). The shift is smaller than in 55% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Castlewood’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. January swings the most: between 1991 and 2020 its average temperature ranged from 0° to 25°. June is the most reliable, staying within 10°.
Common questions about Castlewood’s climate
What is the coldest month in Castlewood?
January, with a typical high of 22° and a low of 3°.
What is the hottest month in Castlewood?
July, with a typical high of 82° and a low of 59°. About 13 days a year reach 90°.
How much snow does Castlewood get?
About 41 inches in a normal winter, most of it in February.
When is the first frost in Castlewood?
In half of years the first 32° night comes by October 1, and the last spring frost by May 6.
What is the rainiest month in Castlewood?
June, with 4.1 inches of rain and melted snow. The year totals 25 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Castlewood itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Watertown Rgnl Airport, SD (10 mi, snow) and Castlewood #2, SD (4 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.