Sioux Falls averages 20.7 days a year above 90°F, with June the wettest month at 4.59 in of normal rain. The hottest day on record was 105°F on Jul 6, 2012; the coldest, −26°F on Jan 30, 2019. The single biggest 24-hour rain event recorded was 4.99 in on Aug 7, 2022.
Climate and Average Weather Year Round in Sioux Falls
Year-round temperature
In Sioux Falls, the warmest months are June through September, with average daily highs between 75°F and 85°F. The coldest stretch runs December through February, with highs between 25°F and 30°F and overnight lows reaching 7°F.
Rainfall through the year
Rainfall in Sioux Falls averages 2.4 in per month over the long run. June is the wettest at 4.6 in, while January is the driest at 0.7 in.
Days at 90 °F or hotter
Sioux Falls averages 20.7 days per year at 90 °F or hotter. The hottest year on record saw 45 such days (2012); the coolest just 2 (2026).
Precipitation this year
As of May 28, Sioux Falls has received 5.7 in of precipitation this year — 39% below the long-term normal for this point in the year (9.3 in).