| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 35°F | 54°F | 44°F | 11.6" |
| February | 39°F | 60°F | 49°F | 2.6" |
| March | 48°F | 70°F | 58°F | 6.5" |
| April | 51°F | 73°F | 62°F | 5.8" |
| May | 63°F | 81°F | 71°F | 8.0" |
| June | 70°F | 90°F | 79°F | 11.0" |
| July | 71°F | 92°F | 80°F | 4.1" |
| August | 73°F | 96°F | 83°F | 1.9" |
| September | 67°F | 91°F | 78°F | 4.9" |
| October | 54°F | 80°F | 66°F | 6.8" |
| November | 47°F | 70°F | 58°F | 4.2" |
| December | 34°F | 60°F | 46°F | 5.3" |
| Index | Princeton | Texas | National |
| Air quality index | 51 | 52 | 42 |
| Pollution index | 723,856 | 2,009,300 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 181 |
| Days with moderate air quality | 155 |
| Days w/ poor A.Q. for sensitive groups | 28 |
| Days with unhealthy air quality | 1 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.003% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Royse City, TX | 14,081 | 51 | 2.0% |
| Fairview, TX | 9,339 | 51 | 2.0% |
| McKinney, TX | 195,852 | 51 | 2.0% |
| Anna, TX | 14,625 | 51 | 2.0% |
| Blue Ridge, TX | 861 | 51 | 2.0% |
| Princeton, TX | 12,578 | 51 | 2.0% |
| City | Population | Air Quality Index | National Avg. |
| Holly Hill, FL | 12,579 | 31 | 38.0% |
| Harrison, WI | 12,579 | 37 | 26.0% |
| Mays Chapel, MD | 12,573 | 46 | 8.0% |
| Ottawa, KS | 12,572 | 41 | 18.0% |
| Santaquin, UT | 12,586 | 46 | 8.0% |
| Princeton, TX | 12,578 | 51 | 2.0% |