| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 43°F | 64°F | 52°F | 2.4" |
| February | 47°F | 69°F | 56°F | 2.1" |
| March | 54°F | 75°F | 63°F | 3.7" |
| April | 61°F | 81°F | 70°F | 4.7" |
| May | 67°F | 87°F | 76°F | 6.0" |
| June | 74°F | 93°F | 83°F | 2.9" |
| July | 75°F | 95°F | 84°F | 2.1" |
| August | 75°F | 97°F | 85°F | 5.4" |
| September | 71°F | 91°F | 79°F | 3.7" |
| October | 61°F | 84°F | 71°F | 2.7" |
| November | 53°F | 74°F | 62°F | 2.7" |
| December | 46°F | 66°F | 54°F | 1.9" |
| Index | Hallettsville | Texas | National |
| Air quality index | 31 | 52 | 42 |
| Pollution index | 1,591,270 | 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 | 0.030% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.010% |
| Mercury | 0.360% |
| City | Population | Air Quality Index | National Avg. |
| Moulton, TX | 980 | 31 | 38.0% |
| Shiner, TX | 2,141 | 31 | 38.0% |
| Yoakum, TX | 5,762 | 31 | 38.0% |
| Hallettsville, TX | 2,613 | 31 | 38.0% |
| City | Population | Air Quality Index | National Avg. |
| Staples, MN | 2,613 | 29 | 42.0% |
| Hudson Oaks, TX | 2,613 | 33 | 34.0% |
| Strathcona C, BC | 2,613 | n/a | |
| Licking, MO | 2,612 | 39 | 22.0% |
| Avoca, PA | 2,612 | 38 | 24.0% |
| Hallettsville, TX | 2,613 | 31 | 38.0% |
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