Ontario, Ohio has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 40.5 °F (low) to 59.1 °F (high). Annual precipitation averages 42 Inches. Ontario is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 17.8 °F | 33.2 °F | 3.19 in. |
| February | 19.3 °F | 35.9 °F | 2.28 in. |
| March | 27.4 °F | 45.7 °F | 2.98 in. |
| April | 38.5 °F | 59.5 °F | 4.01 in. |
| May | 49.9 °F | 70.5 °F | 4.35 in. |
| June | 58.6 °F | 78.5 °F | 4.96 in. |
| July | 61.9 °F | 82.2 °F | 4.28 in. |
| August | 60.1 °F | 80.4 °F | 3.65 in. |
| September | 53.7 °F | 74.6 °F | 3.29 in. |
| October | 42.2 °F | 62.1 °F | 3.04 in. |
| November | 32.1 °F | 48.6 °F | 3.01 in. |
| December | 23.9 °F | 37.9 °F | 2.98 in. |
| Annual | 40.5 °F | 59.1 °F | 42.02 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |