Oswego, Kansas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 47 °F (low) to 67.8 °F (high). Annual precipitation averages 46.1 Inches. Oswego is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 23.8 °F | 43.5 °F | 1.69 in. |
| February | 27.6 °F | 48.5 °F | 1.83 in. |
| March | 36.3 °F | 58.2 °F | 3.2 in. |
| April | 45.9 °F | 67.8 °F | 4.93 in. |
| May | 56.4 °F | 75.9 °F | 7.08 in. |
| June | 65.6 °F | 84.9 °F | 5.57 in. |
| July | 69.8 °F | 89.5 °F | 4.1 in. |
| August | 67.9 °F | 89.4 °F | 3.97 in. |
| September | 59.6 °F | 81.4 °F | 4.55 in. |
| October | 47.6 °F | 70.3 °F | 3.9 in. |
| November | 36.4 °F | 57.6 °F | 2.91 in. |
| December | 27.6 °F | 46.7 °F | 2.35 in. |
| Annual | 47 °F | 67.8 °F | 46.08 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |