| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 30°F | 54°F | 40°F | 2.4" |
| February | 33°F | 56°F | 43°F | 5.0" |
| March | 43°F | 68°F | 54°F | 4.7" |
| April | 51°F | 75°F | 62°F | 8.7" |
| May | 59°F | 80°F | 68°F | 12.5" |
| June | 69°F | 90°F | 79°F | 8.0" |
| July | 71°F | 95°F | 82°F | 7.7" |
| August | 70°F | 94°F | 81°F | 7.9" |
| September | 62°F | 86°F | 73°F | 7.9" |
| October | 51°F | 76°F | 62°F | 11.3" |
| November | 41°F | 65°F | 52°F | 6.8" |
| December | 32°F | 53°F | 41°F | 9.8" |
| Index | Grayson | Oklahoma | National |
| Air quality index | 5 | 55 | 42 |
| Pollution index | 14,334,000 | 1,271,533 | 2,726,193 |
| Measurement | Total |
| Days measured | 286 |
| Days with good air quality | 269 |
| Days with moderate air quality | 15 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality | 1 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.190% |
| Carbon Tetrachloride | 0.040% |
| Lead | 0.170% |
| Mercury | 0.090% |
| City | Population | Air Quality Index | National Avg. |
| Council Hill, OK | 95 | 5 | 90.0% |
| Okmulgee, OK | 11,768 | 5 | 90.0% |
| Schulter, OK | 556 | 5 | 90.0% |
| Hitchita, OK | 60 | 5 | 90.0% |
| Boynton, OK | 151 | 5 | 90.0% |
| Grayson, OK | 178 | 5 | 90.0% |
| City | Population | Air Quality Index | National Avg. |
| Kaktovik, AK | 178 | 38 | 24.0% |
| Kenny Lake, AK | 178 | 31 | 38.0% |
| Gaylesville, AL | 178 | 39 | 22.0% |
| Mount Vernon, AR | 178 | 45 | 10.0% |
| Ravenden Springs, AR | 178 | 26 | 48.0% |
| Grayson, OK | 178 | 5 | 90.0% |
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