Weather in Sioux Falls in August

A good month. August works. It is not the peak, but nothing about it fights you. Highs average 28.9 °C, lows 16.4 °C, and rain falls on 11 days — nothing in the month is working against you.

August ranks 5 of 12 in Sioux Falls: past the worst of the year but short of September, which is the month to book if the dates are open.

Rain on 11 days, 3 of them heavy. Enough to need a plan B, not enough to need a plan around it. Pack for 28.9 °C days and 16.4 °C nights; the spread matters more here than any single number.

What the averages hide

Averages flatten a month, and this one hides a few things: 12 days top 30 °C — hot spells arrive, but they break. Across the twenty years measured, the hottest August day reached 40 °C and the coldest night fell to 7.1 °C, and the wettest single day dropped 46 mm — roughly 55% of the month's rain in one day.

August is moderately variable: 31 mm in the driest year against 157 mm in the wettest, around an average of 83 mm. Roughly two Augusts in three land near that average, and the third does something else entirely.

Wind is light at 9.9 km/h, so the temperature on the page is close to the temperature on your skin, and humidity is unremarkable at 63%.

How August sits in the year

The month is on the way down: 1.8 °C cooler than July, with September dropping another 4.3 °C. The first week and the last are not the same trip.

Daylight in August

14 hours of daylight, losing 1.3 hours across the month. That is between Sioux Falls's extremes of 15.4 and 9 hours, so days are long enough not to constrain the plan.

An inland climate

Sioux Falls has no sea to moderate it, and it shows: 43 °C separates the hottest afternoon of the year from the coldest night. That is a genuinely continental range, and it means summer and winter here are barely the same place.

How busy it gets

Peak season. Expect the highest prices of the year and to be booking well ahead.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

August in Sioux Falls versus nearby

If Sioux Falls is one option among several, the nearby comparison is worth making. Omaha is the weaker option in August — within a degree on temperature, 1 day more rain. Minneapolis is close enough to be a coin toss — within a degree on temperature, 1 day more rain.

So: August works, with September the better month by 13 points if the dates can move. If they cannot, nothing here should stop you booking.

Every month in Sioux Falls

See all twelve months in Sioux Falls, or where else to go in August.