Monthly Climate
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Best time to visit Sioux Falls

September is the best time to visit Sioux Falls for general sightseeing, with average highs of 23 °C and about 8 wet days.

It depends what you are going for

One month rarely wins on everything. These are the best months on each measure taken on its own.

If you want Best month On that measure
Sightseeing and walking September comfort 90/100
The least cloud September 42 % average cloud cover
The least rain January 21 mm
Warmth July 28 °C
Cooler weather January -3.1 °C

Ranked by comfort

# Month Comfort / 100 Avg high Wet days
1 September 90 23 °C 8
2 May 80 21 °C 12
3 August 79 27 °C 9
4 June 79 26 °C 12
5 July 76 28 °C 8
6 October 68 15 °C 7
7 April 58 14 °C 10
8 March 35 7.4 °C 7
9 November 34 6.4 °C 6
10 February 32 0.2 °C 5
11 January 32 -3.1 °C 5
12 December 32 -0.9 °C 5

When to think twice

December scores lowest with about 5 wet days and highs near -0.9 °C. That does not make it a bad month — it depends entirely on what you are travelling for. The numbers are all here; the judgement is yours.

The full year

Month Avg high Rainfall Cloud
January -3.1 °C 21 mm 62 %
February 0.2 °C 24 mm 60 %
March 7.4 °C 48 mm 60 %
April 14.5 °C 90 mm 60 %
May 20.6 °C 111 mm 59 %
June 25.7 °C 133 mm 53 %
July 28.2 °C 81 mm 42 %
August 27.1 °C 84 mm 44 %
September 23.3 °C 77 mm 42 %
October 15.4 °C 61 mm 49 %
November 6.4 °C 40 mm 55 %
December -0.9 °C 27 mm 61 %

Data sources and method

Normal period
1991–2020
Dataset version
era5-1991-2020-scores1.1
Last processed

Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: comfort score, beach score, season boundaries. Full formulas are on the methodology page.

Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.