Weather on August 21
Sioux Falls, SD
55 Years of Data
Avg High
83°F
Avg Low
61°F
Warmest
1976
82°F avg
Coldest
1986
59°F avg
About This Date
August 21st in Sioux Falls, SD typically brings warm summer weather, with average highs around 83°F and lows near 61°F. Over 55 years of records, the warmest August 21st was in 1976 (82°F average), while the coldest was 1986 (59°F) — a 23°F range across recorded history. Rain or other precipitation has occurred on about 25% of August 21st dates historically, with the wettest August 21st recording 5.79" of rain. Temperatures on this date have remained relatively stable over the past several decades.
Temperatures on this date have remained relatively stable over the past several decades.
Planning for August 21st in Sioux Falls, SD? Stay hydrated and seek shade during peak afternoon hours.
Cooling Trend
0.7°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 87° | 63° | 75° | — | — |
| 2024 | 76° | 62° | 69° | — | — |
| 2023 | 96° | 68° | 82° | — | — |
| 2022 | 82° | 56° | 69° | — | — |
| 2021 | 76° | 57° | 66° | — | — |
| 2020 | 93° | 69° | 81° | — | — |
| 2019 | 77° | 59° | 68° | — | — |
| 2018 | 73° | 54° | 63° | — | — |
| 2017 | 74° | 63° | 68° | 5.46" | — |
| 2016 | 80° | 49° | 64° | — | — |
| 2015 | 81° | 62° | 71° | — | — |
| 2014 | 90° | 69° | 79° | — | — |
| 2013 | 81° | 71° | 76° | — | — |
| 2012 | 85° | 49° | 67° | — | — |
| 2011 | 83° | 52° | 67° | — | — |
| 2010 | 91° | 65° | 78° | — | — |
| 2009 | 69° | 54° | 61° | 0.03" | — |
| 2008 | 74° | 65° | 69° | — | — |
| 2007 | 83° | 62° | 72° | 0.03" | — |
| 2006 | 85° | 58° | 71° | — | — |
| 2005 | 79° | 54° | 66° | — | — |
| 2004 | 80° | 40° | 60° | — | — |
| 2003 | 82° | 59° | 71° | — | — |
| 2002 | 83° | 66° | 74° | 5.79" | — |
| 2001 | 80° | 65° | 72° | 0.03" | — |
| 2000 | 78° | 65° | 71° | — | — |
| 1999 | 88° | 66° | 77° | 0.03" | — |
| 1998 | 80° | 65° | 72° | — | — |
| 1997 | 80° | 48° | 64° | — | — |
| 1996 | 86° | 67° | 76° | — | — |
| 1995 | 89° | 59° | 74° | — | — |
| 1994 | 82° | 49° | 65° | — | — |
| 1993 | 81° | 61° | 71° | — | — |
| 1992 | 82° | 65° | 73° | — | — |
| 1991 | 89° | 59° | 74° | — | — |
| 1990 | 74° | 62° | 68° | — | — |
| 1989 | 83° | 61° | 72° | 0.23" | — |
| 1988 | 90° | 66° | 78° | 4.06" | — |
| 1987 | 89° | 65° | 77° | — | — |
| 1986coldest | 73° | 44° | 59° | — | — |
| 1985 | 77° | 60° | 69° | — | — |
| 1984 | 85° | 63° | 74° | 0.28" | — |
| 1983 | 93° | 69° | 81° | — | — |
| 1982 | 85° | 56° | 70° | — | — |
| 1981 | 85° | 62° | 73° | — | — |
| 1980 | 82° | 58° | 70° | — | — |
| 1979 | 79° | 61° | 70° | 0.43" | — |
| 1978 | 86° | 68° | 77° | — | — |
| 1977 | 77° | 57° | 67° | — | — |
| 1976warmest | 95° | 70° | 82° | — | — |
| 1975 | 85° | 68° | 76° | 5.38" | — |
| 1974 | 77° | 59° | 68° | 0.18" | — |
| 1973 | 90° | 67° | 78° | 0.15" | — |
| 1972 | 82° | 63° | 72° | 0.58" | — |
| 1971 | 92° | 66° | 79° | — | — |
55 years of data from SIOUX FALLS