Weather in Sioux Falls in May

A good month. May is a solid month to be in Sioux Falls. Highs average 21.4 °C, lows 8.5 °C, and rain falls on 12 days — nothing in the month is working against you.

May ranks 2 of 12 in Sioux Falls. Only September scores clearly higher, and the difference is small enough to be settled by price rather than weather.

Rain on 12 days, 3 of them heavy. Enough to need a plan B, not enough to need a plan around it. Nothing specialised needed — this is the month you pack for the trip rather than for the weather.

What the averages hide

The averages here are honest — no hidden extremes worth planning around. Across the twenty years measured, the hottest May day reached 34.7 °C and the coldest night fell to -4.7 °C, and the wettest single day dropped 50 mm — roughly 56% of the month's rain in one day.

May is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest May on record still delivered 156 mm against 23 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 90 mm average is a reasonable planning figure, not a promise.

Wind is light at 13.6 km/h, so the temperature on the page is close to the temperature on your skin, and humidity is unremarkable at 66%.

How May sits in the year

The month is on the way up: 6.2 °C warmer than April, and June adds another 5.6 °C. Late in the month feels noticeably different from the start of it, which is worth knowing if the trip is short.

Daylight in May

14.7 hours of daylight, gaining 1.1 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.

May in Sioux Falls versus nearby

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

So: May is effectively as good as it gets here — 6 points behind September, which is inside the margin where the weather stops being the deciding factor and price starts being it.

Every month in Sioux Falls

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