| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 5b: -15°F to -10°F | |
| 2012 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 5b: -15°F to -10°F | |
| 1990 Hardiness Zone: | Zone 1b: -15F to -10F | |
| Average First Frost Date: | Sep. 21 - Sep. 30 | |
| Average Last Frost Date: | May 1 - May 10 | |
| Koppen-Geiger Climate Zone: | Dfa - Humid Continental Hot Summers | |
| Ecoregion: | 25l - Front Range Fans | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | 31 - 45 days Over 86°F |
Annual Climate Data for ZIP Code 80503 - Longmont, CO | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 13 | 18 | 25 | 32 | 42 | 51 | 55 | 54 | 45 | 33 | 23 | 15 | 34 |
| Avg Max Temp (°F) | 42 | 47 | 53 | 62 | 72 | 83 | 89 | 87 | 78 | 67 | 51 | 44 | 65 |
| Avg Precip (In.) | .43 | .39 | 1.22 | 2.03 | 2.45 | 1.74 | 1.14 | 1.39 | 1.36 | .83 | .84 | .58 | 14.4 |