| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 20°F | 35°F | 27°F | 3.3" |
| February | 19°F | 34°F | 26°F | 3.0" |
| March | 29°F | 47°F | 37°F | 3.5" |
| April | 40°F | 62°F | 51°F | 3.3" |
| May | 49°F | 70°F | 59°F | 3.9" |
| June | 59°F | 80°F | 69°F | 5.8" |
| July | 61°F | 82°F | 72°F | 4.1" |
| August | 61°F | 81°F | 71°F | 5.2" |
| September | 54°F | 75°F | 64°F | 3.8" |
| October | 43°F | 62°F | 52°F | 3.9" |
| November | 34°F | 51°F | 42°F | 2.7" |
| December | 24°F | 38°F | 30°F | 3.9" |
| Index | Ontario | Ohio | National |
| Air quality index | 41 | 40 | 42 |
| Pollution index | 1,197,810 | 4,472,386 | 2,726,193 |
| Measurement | Total |
| Days measured | 245 |
| Days with good air quality | 218 |
| Days with moderate air quality | 27 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.010% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Bailey Lakes, OH | 309 | 41 | 18.0% |
| Lucas, OH | 493 | 41 | 18.0% |
| Galion, OH | 10,003 | 41 | 18.0% |
| Crestline, OH | 4,408 | 41 | 18.0% |
| Sulphur Springs, OH | 159 | 41 | 18.0% |
| Ontario, OH | 6,094 | 41 | 18.0% |
| City | Population | Air Quality Index | National Avg. |
| Les Coteaux, QC | 6,094 | n/a | |
| South Gate Ridge, FL | 6,095 | 38 | 24.0% |
| Franklin, PA | 6,092 | 31 | 38.0% |
| Munford, TN | 6,090 | 45 | 10.0% |
| Bridgewater, VA | 6,090 | 36 | 28.0% |
| Ontario, OH | 6,094 | 41 | 18.0% |
Here are the best places to live in Ohio
10 Best cities in Ohio for employment
Top 10 cities in Ohio with the best education system
These are the 10 most affordable cities in Ohio