Last Frost Date Fort Collins: Frost Dates, Late Frost Risk & Growing Season

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

The frost season in Fort Collins

• Last frost (average): May 11
• In 1 year out of 10 it still freezes on May 20.
• First frost: October 4
• Frost-free season: 151 days
• Frost after 15 May: in 27 % of years

Frost days per month in Fort Collins

• January: 29.3 · -6 °C
• February: 26 · -5 °C
• March: 23.4 · -2 °C
• April: 13.8 · 0 °C
• May: 3.1 · 6 °C
• June: 0 · 11 °C
• July: 0 · 16 °C
• August: 0 · 15 °C
• September: 0.6 · 10 °C
• October: 8.2 · 3 °C
• November: 20.9 · -2 °C
• December: 28.7 · -6 °C

• No weather station nearby: plain grid values, which are often a little too cold – dates may therefore be late.
• 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.

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