Altamont, Pennsylvania has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.9 °C (low) to 14.4 °C (high). Annual precipitation averages 1343.7 Millimeters. Altamont is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.2 °C | 0.6 °C | 95.5 mm |
| February | -7.6 °C | 2.1 °C | 75.44 mm |
| March | -3.5 °C | 6.9 °C | 103.63 mm |
| April | 2.7 °C | 14.2 °C | 109.98 mm |
| May | 8.3 °C | 20.2 °C | 115.32 mm |
| June | 13.3 °C | 24.4 °C | 130.05 mm |
| July | 15.9 °C | 27.1 °C | 126.24 mm |
| August | 14.8 °C | 26.1 °C | 117.09 mm |
| September | 11.1 °C | 22.4 °C | 135.89 mm |
| October | 5 °C | 16 °C | 129.29 mm |
| November | -0.4 °C | 9.1 °C | 98.04 mm |
| December | -4.9 °C | 3.3 °C | 107.19 mm |
| Annual | 3.9 °C | 14.4 °C | 1343.66 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |