Big Sioux, SD climate
Big Sioux has cold, snowy winters and warm summers. A typical July afternoon reaches 86°, a January night drops to 10°, and about 36 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Big Sioux feels like
Winter
Spring
Summer
Fall
Big Sioux 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 | 29° | 10° | 0.6" | 7.7" | 7 | 20 | 11° – 33° |
| February | 35° | 14° | 0.8" | 8.7" | 7 | 15 | 13° – 35° |
| March | 48° | 26° | 1.5" | 5.7" | 8 | 7 | 29° – 53° |
| April | 61° | 36° | 3.0" | 2.3" | 10 | 1 | 40° – 55° |
| May | 73° | 48° | 3.9" | 0 | 12 | 0 | 55° – 66° |
| June | 82° | 59° | 4.6" | 0 | 12 | 0 | 67° – 76° |
| July | 86° | 63° | 3.3" | 0 | 9 | 0 | 68° – 81° |
| August | 83° | 61° | 3.7" | 0 | 10 | 0 | 66° – 77° |
| September | 77° | 51° | 2.9" | 0 | 8 | 0 | 58° – 70° |
| October | 63° | 38° | 2.3" | 0.8" | 8 | 0 | 44° – 55° |
| November | 47° | 25° | 1.2" | 3.2" | 6 | 3 | 27° – 46° |
| December | 33° | 15° | 0.9" | 7.6" | 7 | 13 | 11° – 30° |
| Year | 60° | 37° | 28.7" | 36.0" | 102 | 58 |
“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 Big Sioux
Big Sioux gets 29 inches of rain and melted snow a year. June is the wettest month and January the driest. Rain or snow falls on about 102 days a year. Snow covers the ground about 58 days of the year.
About 159 frost-free days a year
In half of years the last 32° night comes by April 29 and the first one by October 5. That leaves about 159 frost-free days for gardens, shorter than 72% of U.S. towns.
Heating and cooling a home in Big Sioux
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Big Sioux, 89% of that work is heating and 11% 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.
Big Sioux and its neighbors
Big Sioux borders 4 towns with climate data. January nights across them vary by 0.4°. Jefferson has the coldest January nights (10°) and Dakota Dunes the hottest July afternoons (86°). Big Sioux’s January low is 10° and its July high 86°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Big Sioux 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 Big Sioux averaged 0.9° warmer than the 1900s. The biggest change is in January (+2.4°). The shift is smaller than in 77% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Big Sioux’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. March swings the most: between 1991 and 2020 its average temperature ranged from 29° to 53°. June is the most reliable, staying within 9°.
Common questions about Big Sioux’s climate
What is the coldest month in Big Sioux?
January, with a typical high of 29° and a low of 10°.
What is the hottest month in Big Sioux?
July, with a typical high of 86° and a low of 63°. About 25 days a year reach 90°.
How much snow does Big Sioux get?
About 36 inches in a normal winter, most of it in February.
When is the first frost in Big Sioux?
In half of years the first 32° night comes by October 5, and the last spring frost by April 29.
What is the rainiest month in Big Sioux?
June, with 4.6 inches of rain and melted snow. The year totals 29 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Big Sioux itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Sioux City Gateway Airport, IA (11 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.