Weir, Mississippi has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 11 °C (low) to 23.4 °C (high). Annual precipitation averages 1460.3 Millimeters. Weir is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 0.7 °C | 12.4 °C | 130.81 mm |
| February | 2.3 °C | 14.9 °C | 134.11 mm |
| March | 6.1 °C | 19.4 °C | 138.94 mm |
| April | 10.4 °C | 23.8 °C | 150.88 mm |
| May | 15.4 °C | 27.8 °C | 118.87 mm |
| June | 19.6 °C | 31.3 °C | 113.28 mm |
| July | 21.3 °C | 32.7 °C | 120.4 mm |
| August | 20.7 °C | 32.4 °C | 109.98 mm |
| September | 17.3 °C | 29.9 °C | 97.28 mm |
| October | 10.9 °C | 24.7 °C | 93.73 mm |
| November | 5 °C | 18.3 °C | 112.52 mm |
| December | 2.1 °C | 13.7 °C | 139.45 mm |
| Annual | 11 °C | 23.4 °C | 1460.25 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 8a : -12.2°C to -9.4°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |