| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 20°F | 37°F | 28°F | 2.6" |
| February | 21°F | 39°F | 29°F | 3.2" |
| March | 34°F | 55°F | 43°F | 4.1" |
| April | 44°F | 67°F | 55°F | 6.7" |
| May | 54°F | 76°F | 65°F | 4.6" |
| June | 63°F | 85°F | 74°F | 8.5" |
| July | 66°F | 87°F | 76°F | 11.2" |
| August | 64°F | 86°F | 74°F | 8.1" |
| September | 56°F | 80°F | 67°F | 11.5" |
| October | 46°F | 68°F | 56°F | 6.3" |
| November | 34°F | 54°F | 43°F | 5.1" |
| December | 25°F | 40°F | 32°F | 5.3" |
| Index | San Jose | Illinois | National |
| Air quality index | 41 | 41 | 50 |
| Pollution index | 1,277,890 | 3,347,295 | 5,066,862 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 285 |
| Days with moderate air quality | 78 |
| Days w/ poor A.Q. for sensitive groups | 2 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.050% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.010% |
| Mercury | 0.002% |
| City, State | Population | Air Quality Index | National Avg. |
| New Holland, IL | 187 | 40 | 20% |
| Lincoln, IL | 14,253 | 40 | 20% |
| Easton, IL | 376 | 40 | 20% |
| Mason City, IL | 2,272 | 40 | 20% |
| Middletown, IL | 323 | 40 | 20% |
| San Jose, IL | 645 | 41 | 18% |
| City, State | Population | Air Quality Index | National Avg. |
| Stratford, IA | 645 | 37 | 26% |
| South Webster, OH | 645 | 14 | 72% |
| Cordova, IL | 645 | 42 | 16% |
| Greenville, IN | 645 | 49 | 2% |
| York Haven, PA | 645 | 41 | 18% |
| San Jose, IL | 645 | 41 | 18% |
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