Arthur, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 36.8 °F (low) to 58.3 °F (high). Annual precipitation averages 32.2 Inches. Arthur is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 9.1 °F | 27.6 °F | 0.75 in. |
| February | 13.2 °F | 32.2 °F | 0.91 in. |
| March | 24.6 °F | 45.7 °F | 1.77 in. |
| April | 35.5 °F | 59.5 °F | 3.4 in. |
| May | 48.0 °F | 70.8 °F | 4.48 in. |
| June | 59.0 °F | 80.9 °F | 5.06 in. |
| July | 62.7 °F | 83.8 °F | 3.64 in. |
| August | 59.9 °F | 81.7 °F | 4.34 in. |
| September | 50.8 °F | 75.9 °F | 3.01 in. |
| October | 38.2 °F | 62.5 °F | 2.29 in. |
| November | 25.3 °F | 46.1 °F | 1.4 in. |
| December | 15.1 °F | 32.6 °F | 1.1 in. |
| Annual | 36.8 °F | 58.3 °F | 32.15 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |