Holtsville, New York has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 44.9 °F (low) to 61.3 °F (high). Annual precipitation averages 50.5 Inches. Holtsville is located in USDA Plant Hardiness Zone 7b. 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 | 24.2 °F | 39.6 °F | 3.92 in. |
| February | 25.3 °F | 41.3 °F | 3.61 in. |
| March | 31.6 °F | 48.0 °F | 5.11 in. |
| April | 40.8 °F | 58.6 °F | 4.32 in. |
| May | 50.6 °F | 68.5 °F | 3.94 in. |
| June | 60.5 °F | 77.5 °F | 4.37 in. |
| July | 66.5 °F | 83.1 °F | 3.36 in. |
| August | 65.3 °F | 81.4 °F | 4.14 in. |
| September | 58.6 °F | 75.2 °F | 4.01 in. |
| October | 47.7 °F | 64.3 °F | 4.87 in. |
| November | 37.5 °F | 53.6 °F | 3.86 in. |
| December | 29.9 °F | 45.0 °F | 5.01 in. |
| Annual | 44.9 °F | 61.3 °F | 50.52 in. |
| 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 7b : 5°F to 10°F |
| Plant Hardiness Zone - 2012 | Zone 7a : 0°F to 5°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |