| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 36°F | 58°F | 45°F | 5.9" |
| February | 39°F | 61°F | 49°F | 5.6" |
| March | 47°F | 70°F | 57°F | 8.2" |
| April | 54°F | 77°F | 64°F | 8.9" |
| May | 61°F | 83°F | 71°F | 6.0" |
| June | 70°F | 91°F | 79°F | 6.0" |
| July | 72°F | 94°F | 82°F | 3.4" |
| August | 72°F | 94°F | 82°F | 10.4" |
| September | 65°F | 88°F | 76°F | 14.7" |
| October | 53°F | 79°F | 65°F | 15.7" |
| November | 45°F | 68°F | 55°F | 8.1" |
| December | 38°F | 59°F | 47°F | 10.1" |
| Index | Winnsboro | Texas | National |
| Air quality index | 37 | 52 | 42 |
| Pollution index | 2,654,360 | 2,009,300 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 289 |
| Days with moderate air quality | 67 |
| Days w/ poor A.Q. for sensitive groups | 9 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.003% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Como, TX | 732 | 36 | 28.0% |
| Quitman, TX | 2,398 | 36 | 28.0% |
| Winfield, TX | 553 | 37 | 26.0% |
| Miller's Cove, TX | 149 | 37 | 26.0% |
| Winnsboro, TX | 3,408 | 37 | 26.0% |
| City | Population | Air Quality Index | National Avg. |
| Hartford, SD | 3,408 | 36 | 28.0% |
| Old Mystic, CT | 3,409 | 37 | 26.0% |
| Long Prairie, MN | 3,409 | 29 | 42.0% |
| Cottondale, AL | 3,406 | 35 | 30.0% |
| Auberry, CA | 3,406 | 60 | 20.0% |
| Winnsboro, TX | 3,408 | 37 | 26.0% |