| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | -2.9° | -13.1° | 16.7mm | 6.8 | 16 |
| February | -0.4° | -11.3° | 20.3mm | 6.6 | 17 |
| March | 6.7° | -4.7° | 40.7mm | 8.1 | 31 |
| April | 14.6° | 1.5° | 76.3mm | 10.1 | 62 |
| May | 21° | 8.2° | 93.5mm | 12.3 | 75 |
| June | 27° | 14.5° | 102.5mm | 11.5 | 77 |
| July | 29.5° | 17.3° | 73.7mm | 8.4 | 73 |
| August | 27.9° | 16° | 91.1mm | 9.2 | 78 |
| September | 24.3° | 11° | 64.6mm | 8 | 84 |
| October | 16° | 3.3° | 58.7mm | 8 | 71 |
| November | 7.4° | -4.3° | 29.1mm | 5.8 | 39 |
| December | -0.4° | -10.5° | 25.3mm | 7 | 16 |
January in Sioux Falls averages a daily high of -2.9°C with nights around -13.1°C. Expect roughly 6.8 wet days totalling 16.7mm. A hard month to visit for comfort alone.
February in Sioux Falls averages a daily high of -0.4°C with nights around -11.3°C. Expect roughly 6.6 wet days totalling 20.3mm. A hard month to visit for comfort alone.
March in Sioux Falls averages a daily high of 6.7°C with nights around -4.7°C. Expect roughly 8.1 wet days totalling 40.7mm. A hard month to visit for comfort alone.
April in Sioux Falls averages a daily high of 14.6°C with nights around 1.5°C. Expect roughly 10.1 wet days totalling 76.3mm. Generally workable, with some weather to plan around.
May in Sioux Falls averages a daily high of 21°C with nights around 8.2°C. Expect roughly 12.3 wet days totalling 93.5mm. Comfortable conditions for being outdoors all day.
June in Sioux Falls averages a daily high of 27°C with nights around 14.5°C. Expect roughly 11.5 wet days totalling 102.5mm. Comfortable conditions for being outdoors all day.
July in Sioux Falls averages a daily high of 29.5°C with nights around 17.3°C. Expect roughly 8.4 wet days totalling 73.7mm. Generally workable, with some weather to plan around.
August in Sioux Falls averages a daily high of 27.9°C with nights around 16°C. Expect roughly 9.2 wet days totalling 91.1mm. Comfortable conditions for being outdoors all day.
September in Sioux Falls averages a daily high of 24.3°C with nights around 11°C. Expect roughly 8 wet days totalling 64.6mm. Comfortable conditions for being outdoors all day.
October in Sioux Falls averages a daily high of 16°C with nights around 3.3°C. Expect roughly 8 wet days totalling 58.7mm. Generally workable, with some weather to plan around.
November in Sioux Falls averages a daily high of 7.4°C with nights around -4.3°C. Expect roughly 5.8 wet days totalling 29.1mm. Demanding conditions — pack for it and plan indoor options.
December in Sioux Falls averages a daily high of -0.4°C with nights around -10.5°C. Expect roughly 7 wet days totalling 25.3mm. A hard month to visit for comfort alone.
Each month scores out of 100. It starts at 100 and loses points for daytime highs outside a 20–27°C band, for wet days, and for nights below 2°C. Nothing else is weighted in — no crowd data, no prices, no opinion. Sioux Falls peaks at 84.
Based on 30 years of records, August–September scores highest for comfort in Sioux Falls, balancing daytime temperature against rainfall.
July is the warmest, averaging a daily high of 29.5°C.
June is the wettest, averaging 102.5mm of rain across roughly 11.5 wet days.
January is the coolest month, with average daily highs around -2.9°C.