Last Frost Date Wyoming: Frost Dates, Late Frost Risk & Growing Season

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

The frost season in Wyoming

Last frost (average): April 26
In 1 year out of 10 it still freezes on May 8.
First frost: October 25
Frost-free season: 180 days
Frost after 15 May: in 3 % of years

Frost days per month in Wyoming

January: 28.3 · -7 °C
February: 25.7 · -7 °C
March: 23 · -3 °C
April: 8.2 · 3 °C
May: 0.3 · 9 °C
June: 0 · 15 °C
July: 0 · 17 °C
August: 0 · 16 °C
September: 0 · 12 °C
October: 2.1 · 6 °C
November: 15.3 · 0 °C
December: 25.8 · -4 °C

Matched to the average lows of a weather station 15 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.