| 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 | Smithville | Texas | National |
| Air quality index | 44 | 52 | 42 |
| Pollution index | 1,591,270 | 2,009,300 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 249 |
| Days with moderate air quality | 114 |
| Days w/ poor A.Q. for sensitive groups | 2 |
| 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. |
| Giddings, TX | 5,095 | 44 | 12.0% |
| Bastrop, TX | 9,094 | 44 | 12.0% |
| Camp Swift, TX | 6,529 | 44 | 12.0% |
| Circle D-KC Estates, TX | 2,761 | 44 | 12.0% |
| Smithville, TX | 4,501 | 44 | 12.0% |
| City | Population | Air Quality Index | National Avg. |
| New Roads, LA | 4,500 | 45 | 10.0% |
| Louisburg, KS | 4,499 | 47 | 6.0% |
| Royal Pines, NC | 4,499 | 44 | 12.0% |
| Heeia, HI | 4,503 | 30 | 40.0% |
| Jonesboro, LA | 4,503 | 34 | 32.0% |
| Smithville, TX | 4,501 | 44 | 12.0% |
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