Frost dates in Colorado

Colorado cities

• Frost dates in Denver: last frost May 4, first frost October 8
• Frost dates in Colorado Springs: last frost May 3, first frost October 8
• Frost dates in Aurora: last frost May 4, first frost October 8
• Frost dates in Fort Collins: last frost May 2, first frost October 7
• Frost dates in Lakewood: last frost May 3, first frost October 7
• Frost dates in Thornton: last frost May 2, first frost October 11

Find yours by ZIP code

The table below is by weather station. For the station nearest you, and your planting zone, type your ZIP code.

Colorado frost dates by weather station

The average date is NOAA's 50% date: half of years have a later last frost, or an earlier first one. Plan by the 1-in-10 date if a freeze would cost you plants. Stations are NOAA's main weather stations, mostly airports. “Zone nearby” is the USDA 2023 zone of the nearest ZIP code within 10 miles. NOAA counts the frost season from August to July, so in the warmest places the “first fall” freeze lands after New Year.

How these dates work

Frost dates come from NOAA's 1991 to 2020 Climate Normals, which work out from each weather station's daily lows how likely the last spring freeze and the first fall freeze (32 °F) are by each date. We use the station nearest the middle of your ZIP code and show its height and distance, since a station on a hill or by a lake can differ from your yard.

The average date is the 50% date: half of years have a freeze after the spring date or before the fall one. The 1-in-10 dates are NOAA's 10% dates, the ones to plan by if a late freeze would cost you plants. Within one yard, cold air pools in low spots while walls and paving hold heat, so some corners freeze before others.

Other states

Alabama · Alaska · Arizona · Arkansas · California · Connecticut · Delaware · Florida · Georgia · Hawaii · Idaho · Illinois · Indiana · Iowa · Kansas · Kentucky · Louisiana · Maine · Maryland · Massachusetts · Michigan · Minnesota · Mississippi · Missouri · Montana · Nebraska · Nevada · New Hampshire · New Jersey · New Mexico · New York · North Carolina · North Dakota · Ohio · Oklahoma · Oregon · Pennsylvania · Rhode Island · South Carolina · South Dakota · Tennessee · Texas · Utah · Vermont · Virginia · Washington · West Virginia · Wisconsin · Wyoming

Where the numbers come from

• USDA Plant Hardiness Zone Map, 2023. Agricultural Research Service, U.S. Department of Agriculture
• PRISM Climate Group, Oregon State University (zone data)
• NOAA NCEI, U.S. Climate Normals 1991–2020, annual/seasonal
• NOAA, Normals calculation methodology (frost-freeze probability dates)
• US Census Bureau, 2025 ZCTA gazetteer (ZIP code centers)