Olean, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 35.3 °F (low) to 57.1 °F (high). Annual precipitation averages 41 Inches. Olean is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 14.4 °F | 31.8 °F | 2.81 in. |
| February | 14.9 °F | 34.3 °F | 2.04 in. |
| March | 21.4 °F | 43.2 °F | 2.71 in. |
| April | 31.8 °F | 56.4 °F | 3.37 in. |
| May | 42.9 °F | 68.8 °F | 3.68 in. |
| June | 51.6 °F | 76.5 °F | 4.47 in. |
| July | 55.9 °F | 80.1 °F | 4.34 in. |
| August | 55.2 °F | 78.6 °F | 4.08 in. |
| September | 48.3 °F | 72.1 °F | 3.9 in. |
| October | 37.5 °F | 59.9 °F | 3.6 in. |
| November | 28.9 °F | 47.2 °F | 2.96 in. |
| December | 21.2 °F | 36.6 °F | 3.07 in. |
| Annual | 35.3 °F | 57.1 °F | 41.03 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |