| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 51°F | 72°F | 60°F | 2.9" |
| February | 55°F | 77°F | 64°F | 2.4" |
| March | 61°F | 82°F | 70°F | 4.1" |
| April | 67°F | 88°F | 76°F | 4.4" |
| May | 72°F | 91°F | 80°F | 7.5" |
| June | 76°F | 96°F | 84°F | 6.0" |
| July | 76°F | 96°F | 85°F | 12.6" |
| August | 77°F | 97°F | 86°F | 6.9" |
| September | 74°F | 93°F | 81°F | 9.5" |
| October | 67°F | 89°F | 77°F | 11.2" |
| November | 59°F | 81°F | 69°F | 4.4" |
| December | 54°F | 74°F | 62°F | 4.7" |
| Index | Heidelberg | Texas | National |
| Air quality index | 42 | 52 | 42 |
| Pollution index | 7,136,530 | 2,009,300 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 243 |
| Days with moderate air quality | 120 |
| Days w/ poor A.Q. for sensitive groups | 2 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.080% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.020% |
| Mercury | 0.001% |
| City | Population | Air Quality Index | National Avg. |
| Progreso, TX | 5,908 | 42 | 16.0% |
| Midway South, TX | 2,293 | 42 | 16.0% |
| Villa Verde, TX | 203 | 42 | 16.0% |
| North Alamo, TX | 3,977 | 42 | 16.0% |
| Ratamosa, TX | 99 | 42 | 16.0% |
| Heidelberg, TX | 1,724 | 42 | 16.0% |
| City | Population | Air Quality Index | National Avg. |
| Hazen, AR | 1,724 | 45 | 10.0% |
| De Pue, IL | 1,724 | 0 | 100.0% |
| Mechanicsville, MD | 1,724 | 47 | 6.0% |
| Runaway Bay, TX | 1,724 | 33 | 34.0% |
| Duxbury, MA | 1,723 | 43 | 14.0% |
| Heidelberg, TX | 1,724 | 42 | 16.0% |
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