Bethany, Connecticut has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.8 °C (low) to 15.4 °C (high). Annual precipitation averages 1345.4 Millimeters. Bethany is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7.2 °C | 2 °C | 102.11 mm |
| February | -6.4 °C | 3.4 °C | 87.88 mm |
| March | -2.4 °C | 7.8 °C | 121.92 mm |
| April | 3.3 °C | 14.7 °C | 110.49 mm |
| May | 8.7 °C | 20.7 °C | 110.49 mm |
| June | 13.9 °C | 25.4 °C | 114.3 mm |
| July | 16.9 °C | 28.2 °C | 107.19 mm |
| August | 16.2 °C | 27.2 °C | 107.95 mm |
| September | 12.3 °C | 23.2 °C | 119.63 mm |
| October | 5.8 °C | 16.8 °C | 139.19 mm |
| November | 0.7 °C | 10.5 °C | 107.19 mm |
| December | -3.9 °C | 4.7 °C | 117.09 mm |
| Annual | 4.8 °C | 15.4 °C | 1345.43 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |