Saco, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.7 °C (low) to 14.2 °C (high). Annual precipitation averages 1233.9 Millimeters. Saco is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.3 °C | 0.9 °C | 90.17 mm |
| February | -8.4 °C | 2.1 °C | 91.69 mm |
| March | -3.6 °C | 6.3 °C | 116.59 mm |
| April | 2.1 °C | 12.8 °C | 109.47 mm |
| May | 7.6 °C | 18.9 °C | 91.44 mm |
| June | 12.9 °C | 24.1 °C | 110.24 mm |
| July | 16.3 °C | 27 °C | 77.98 mm |
| August | 15.6 °C | 26.5 °C | 86.87 mm |
| September | 11.5 °C | 22.6 °C | 94.23 mm |
| October | 5.4 °C | 15.9 °C | 135.64 mm |
| November | -0.1 °C | 9.7 °C | 111.25 mm |
| December | -5.3 °C | 4.1 °C | 118.36 mm |
| Annual | 3.7 °C | 14.2 °C | 1233.93 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |