Agar, South Dakota has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 33.6 °F (low) to 57.2 °F (high). Annual precipitation averages 20.2 Inches. Agar is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 6.2 °F | 26.2 °F | 0.42 in. |
| February | 10.1 °F | 30.7 °F | 0.63 in. |
| March | 20.5 °F | 43.4 °F | 0.85 in. |
| April | 31.9 °F | 57.2 °F | 1.89 in. |
| May | 43.9 °F | 68.8 °F | 3.1 in. |
| June | 54.6 °F | 78.7 °F | 3.52 in. |
| July | 60.1 °F | 86.1 °F | 2.7 in. |
| August | 58.2 °F | 84.9 °F | 2.42 in. |
| September | 48.9 °F | 76.3 °F | 1.75 in. |
| October | 35.3 °F | 60.0 °F | 1.83 in. |
| November | 22.2 °F | 43.8 °F | 0.58 in. |
| December | 11.3 °F | 30.4 °F | 0.5 in. |
| Annual | 33.6 °F | 57.2 °F | 20.19 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4b : -25°F to -20°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |