Princeton, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 40.6 °F (low) to 59.8 °F (high). Annual precipitation averages 38.6 Inches. Princeton is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 13.9 °F | 30.0 °F | 1.54 in. |
| February | 17.5 °F | 34.5 °F | 1.77 in. |
| March | 28.3 °F | 47.4 °F | 2.5 in. |
| April | 39.4 °F | 60.9 °F | 3.74 in. |
| May | 51.2 °F | 72.2 °F | 4.76 in. |
| June | 61.3 °F | 81.5 °F | 4.98 in. |
| July | 64.9 °F | 84.5 °F | 4.45 in. |
| August | 62.7 °F | 82.5 °F | 4.08 in. |
| September | 54.4 °F | 76.6 °F | 3.57 in. |
| October | 42.6 °F | 63.7 °F | 2.84 in. |
| November | 30.6 °F | 48.6 °F | 2.27 in. |
| December | 20.2 °F | 35.5 °F | 2.06 in. |
| Annual | 40.6 °F | 59.8 °F | 38.56 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |