| 2023 Hardiness Zone: | Zone 5a: -20°F to -15°F | |
| 2012 Hardiness Zone: | Zone 5a: -20°F to -15°F | |
| 1990 Hardiness Zone: | Zone 4b: -25F to -20F | |
| 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: | 47a - Loess Prairies | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 51301 - Spencer, IA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 5 | 12 | 24 | 35 | 47 | 57 | 62 | 59 | 49 | 37 | 23 | 10 | 35 |
| Avg Max Temp (°F) | 24 | 30 | 42 | 58 | 71 | 80 | 84 | 81 | 74 | 61 | 42 | 28 | 56 |
| Avg Precip (In.) | .58 | .55 | 1.9 | 3.05 | 3.68 | 4.17 | 4.01 | 4.17 | 2.78 | 2.02 | 1.48 | .65 | 29.05 |