Smithtown, New York has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 45 °F (low) to 61.4 °F (high). Annual precipitation averages 50.4 Inches. Smithtown 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 | 39.3 °F | 3.89 in. |
| February | 25.3 °F | 41.1 °F | 3.48 in. |
| March | 31.6 °F | 47.9 °F | 4.89 in. |
| April | 41.0 °F | 59.4 °F | 4.35 in. |
| May | 50.7 °F | 69.2 °F | 3.92 in. |
| June | 60.6 °F | 77.9 °F | 4.35 in. |
| July | 66.6 °F | 83.3 °F | 3.43 in. |
| August | 65.5 °F | 81.6 °F | 4.23 in. |
| September | 58.7 °F | 75.1 °F | 4.09 in. |
| October | 47.8 °F | 63.9 °F | 4.95 in. |
| November | 37.6 °F | 53.7 °F | 3.76 in. |
| December | 30.1 °F | 44.7 °F | 5.03 in. |
| Annual | 45 °F | 61.4 °F | 50.37 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 |