Olean, Missouri has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 7.3 °C (low) to 18.9 °C (high). Annual precipitation averages 1111.8 Millimeters. Olean is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.7 °C | 4.8 °C | 55.37 mm |
| February | -3.6 °C | 7.6 °C | 53.34 mm |
| March | 1.1 °C | 13.3 °C | 75.44 mm |
| April | 6.8 °C | 19.4 °C | 124.46 mm |
| May | 12.7 °C | 24.2 °C | 133.86 mm |
| June | 17.7 °C | 28.7 °C | 118.62 mm |
| July | 19.9 °C | 31.1 °C | 108.2 mm |
| August | 18.8 °C | 30.7 °C | 100.08 mm |
| September | 14.1 °C | 26.7 °C | 113.79 mm |
| October | 7.7 °C | 20.5 °C | 89.15 mm |
| November | 1.7 °C | 13.1 °C | 81.03 mm |
| December | -3.4 °C | 7 °C | 58.42 mm |
| Annual | 7.3 °C | 18.9 °C | 1111.76 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |