Oswego, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 41 °F (low) to 55.4 °F (high). Annual precipitation averages 43.3 Inches. Oswego is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 18.1 °F | 31.6 °F | 3.82 in. |
| February | 19.5 °F | 33.0 °F | 2.9 in. |
| March | 26.3 °F | 39.9 °F | 3.03 in. |
| April | 36.9 °F | 51.7 °F | 3.46 in. |
| May | 47.8 °F | 64.3 °F | 3.33 in. |
| June | 57.3 °F | 73.3 °F | 3.37 in. |
| July | 63.4 °F | 78.4 °F | 3.39 in. |
| August | 62.2 °F | 77.8 °F | 3.45 in. |
| September | 55.2 °F | 71.3 °F | 3.89 in. |
| October | 44.7 °F | 58.8 °F | 4.59 in. |
| November | 35.0 °F | 47.8 °F | 4.11 in. |
| December | 25.4 °F | 37.2 °F | 3.91 in. |
| Annual | 41 °F | 55.4 °F | 43.25 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |