Bay City, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 15.8 °C (low) to 26.4 °C (high). Annual precipitation averages 1246.1 Millimeters. Bay City is located in USDA Plant Hardiness Zone 9b.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 6.7 °C | 17.7 °C | 93.98 mm |
| February | 8.8 °C | 19.7 °C | 67.31 mm |
| March | 12.2 °C | 22.9 °C | 80.26 mm |
| April | 15.4 °C | 26.1 °C | 82.04 mm |
| May | 19.8 °C | 29.4 °C | 112.27 mm |
| June | 22.9 °C | 32.3 °C | 140.97 mm |
| July | 23.6 °C | 33.2 °C | 98.04 mm |
| August | 23.5 °C | 34 °C | 114.81 mm |
| September | 21.3 °C | 31.8 °C | 139.19 mm |
| October | 16.3 °C | 28.2 °C | 123.95 mm |
| November | 11.3 °C | 23 °C | 97.79 mm |
| December | 7.8 °C | 18.9 °C | 95.5 mm |
| Annual | 15.8 °C | 26.4 °C | 1246.11 mm |
| Average First Frost Date | Frost Rare |
| Average Last Frost Date | |
| Average Days With Frost | Frost Rare |
| Plant Hardiness Zone | Zone 9b : -3.9°C to -1.1°C |
| Plant Hardiness Zone - 2012 | Zone 9a : -6.7°C to -3.9°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |