Last Frost Date Sioux City: Frost Dates, Late Frost Risk & Growing Season

When is the last spring frost and the first autumn frost in Sioux City? Frost dates from 30 years of data, the risk of late frost, frost-free days and planting dates.

The frost season in Sioux City

Last frost (average): April 27
In 1 year out of 10 it still freezes on May 11.
First frost: October 7
Frost-free season: 165 days
Frost after 15 May: in 3 % of years

Frost days per month in Sioux City

January: 31 · -12 °C
February: 27.6 · -9 °C
March: 24.4 · -3 °C
April: 9.3 · 3 °C
May: 0.5 · 9 °C
June: 0 · 15 °C
July: 0 · 18 °C
August: 0 · 16 °C
September: 0.2 · 11 °C
October: 8.2 · 3 °C
November: 24.3 · -4 °C
December: 30.7 · -9 °C

Matched to the average lows of a weather station 11 km away – accurate to about ±1–2 weeks.
Daily minimum temperatures 2 m above ground over 30 years (1991–2020), NASA POWER; station data: Deutscher Wetterdienst (CC BY 4.0). Ground frost can form while the air at 2 m is still +2 to +3 °C.