| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 34°F | 57°F | 44°F | 4.7" |
| February | 32°F | 56°F | 43°F | 4.9" |
| March | 40°F | 67°F | 53°F | 9.2" |
| April | 46°F | 73°F | 59°F | 5.1" |
| May | 54°F | 80°F | 67°F | 3.1" |
| June | 65°F | 87°F | 75°F | 7.7" |
| July | 69°F | 90°F | 78°F | 6.0" |
| August | 71°F | 93°F | 81°F | 3.6" |
| September | 63°F | 88°F | 75°F | 1.5" |
| October | 54°F | 77°F | 64°F | 3.9" |
| November | 39°F | 66°F | 52°F | 4.6" |
| December | 34°F | 58°F | 44°F | 7.2" |
| Index | Irwin | South Carolina | National |
| Air quality index | 49 | 37 | 42 |
| Pollution index | 2,035,010 | 3,620,438 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 200 |
| Days with moderate air quality | 147 |
| Days w/ poor A.Q. for sensitive groups | 18 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.020% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.010% |
| Mercury | 0.004% |
| City | Population | Air Quality Index | National Avg. |
| Great Falls, SC | 1,806 | 43 | 14.0% |
| Heath Springs, SC | 639 | 43 | 14.0% |
| Kershaw, SC | 1,765 | 43 | 14.0% |
| Catawba, SC | 1,069 | 49 | 2.0% |
| Richburg, SC | 349 | 49 | 2.0% |
| Irwin, SC | 1,308 | 49 | 2.0% |
| City | Population | Air Quality Index | National Avg. |
| Bagley, MN | 1,308 | 33 | 34.0% |
| Mogul, NV | 1,308 | 46 | 8.0% |
| Miltonvale Park, PE | 1,308 | n/a | |
| Saint-Mathieu-du-Parc, QC | 1,308 | n/a | |
| Sifton, MB | 1,308 | n/a | |
| Irwin, SC | 1,308 | 49 | 2.0% |
Here are the best places to live in South Carolina
Top 10 cities in South Carolina with the best education system
10 Best cities in South Carolina for employment
Check out the 10 safest cities in South Carolina