| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 46°F | 66°F | 54°F | 2.8" |
| February | 50°F | 69°F | 58°F | 1.9" |
| March | 56°F | 75°F | 65°F | 2.5" |
| April | 62°F | 80°F | 71°F | 3.4" |
| May | 69°F | 85°F | 76°F | 3.4" |
| June | 74°F | 91°F | 82°F | 2.5" |
| July | 75°F | 92°F | 83°F | 2.3" |
| August | 75°F | 93°F | 83°F | 5.0" |
| September | 71°F | 89°F | 79°F | 3.1" |
| October | 62°F | 84°F | 72°F | 2.3" |
| November | 55°F | 75°F | 64°F | 2.3" |
| December | 49°F | 68°F | 57°F | 2.2" |
| Index | Bay City | Texas | National |
| Air quality index | 31 | 52 | 42 |
| Pollution index | 1,269,560 | 2,009,300 | 2,726,193 |
| Measurement | Total |
| Days measured | 341 |
| Days with good air quality | 319 |
| Days with moderate air quality | 22 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.003% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.003% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Markham, TX | 1,063 | 31 | 38.0% |
| Van Vleck, TX | 1,326 | 52 | 4.0% |
| Bay City, TX | 18,090 | 31 | 38.0% |
| City | Population | Air Quality Index | National Avg. |
| Kingsland, GA | 18,088 | 36 | 28.0% |
| North Grenville, ON | 18,083 | n/a | |
| Otsego, MN | 18,078 | 46 | 8.0% |
| Pelham, ON | 18,077 | n/a | |
| Greenfield Town, MA | 18,076 | 34 | 32.0% |
| Bay City, TX | 18,090 | 31 | 38.0% |