Key Biscayne, Florida has a Tropical Monsoon climate (Köppen classification: Am). Average annual temperatures range from 71.8 °F (low) to 82 °F (high). Annual precipitation averages 57.6 Inches. Key Biscayne is located in USDA Plant Hardiness Zone 11a.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 62.3 °F | 74.8 °F | 2.21 in. |
| February | 64.1 °F | 76.1 °F | 2.16 in. |
| March | 66.6 °F | 77.7 °F | 2.39 in. |
| April | 70.7 °F | 80.6 °F | 3.14 in. |
| May | 74.5 °F | 83.6 °F | 5.42 in. |
| June | 77.3 °F | 86.6 °F | 8.23 in. |
| July | 78.8 °F | 88.2 °F | 5.85 in. |
| August | 78.9 °F | 88.5 °F | 7.33 in. |
| September | 77.9 °F | 87.2 °F | 8.31 in. |
| October | 75.2 °F | 84.4 °F | 6.86 in. |
| November | 69.7 °F | 79.9 °F | 3.33 in. |
| December | 65.8 °F | 76.8 °F | 2.33 in. |
| Annual | 71.8 °F | 82 °F | 57.56 in. |
| Average First Frost Date | No Frost |
| Average Last Frost Date | |
| Average Days With Frost | Frost Free |
| Plant Hardiness Zone | Zone 11a : 40°F to 35°F |
| Plant Hardiness Zone - 2012 | Zone 11a : 40°F to 35°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Am - Tropical Monsoon |