| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 50°F | 73°F | 60°F | 1.3" |
| February | 54°F | 77°F | 64°F | 0.8" |
| March | 60°F | 82°F | 69°F | 1.3" |
| April | 66°F | 88°F | 76°F | 1.4" |
| May | 71°F | 91°F | 80°F | 2.9" |
| June | 74°F | 95°F | 84°F | 1.7" |
| July | 76°F | 96°F | 84°F | 3.1" |
| August | 76°F | 97°F | 85°F | 2.2" |
| September | 73°F | 93°F | 81°F | 5.4" |
| October | 66°F | 89°F | 76°F | 2.1" |
| November | 58°F | 81°F | 68°F | 2.1" |
| December | 53°F | 74°F | 62°F | 1.6" |
| Index | Harlingen | Texas | National |
| Air quality index | 44 | 52 | 42 |
| Pollution index | 7,136,530 | 2,009,300 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 236 |
| Days with moderate air quality | 129 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| 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. |
| Sebastian, TX | 1,508 | 42 | 16.0% |
| Laguna Seca, TX | 244 | 42 | 16.0% |
| Tierra Bonita, TX | 65 | 42 | 16.0% |
| La Villa, TX | 2,791 | 42 | 16.0% |
| Zapata Ranch, TX | 216 | 42 | 16.0% |
| Harlingen, TX | 65,028 | 44 | 12.0% |
| City | Population | Air Quality Index | National Avg. |
| Santa Cruz, CA | 65,011 | 35 | 30.0% |
| Laguna Niguel, CA | 65,048 | 89 | 78.0% |
| Blaine, MN | 65,048 | 46 | 8.0% |
| Wellington, FL | 64,990 | 36 | 28.0% |
| Bethesda, MD | 65,092 | 47 | 6.0% |
| Harlingen, TX | 65,028 | 44 | 12.0% |
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