Key Biscayne, Florida has a Tropical Monsoon climate (Köppen classification: Am). Average annual temperatures range from 22.1 °C (low) to 27.8 °C (high). Annual precipitation averages 1462 Millimeters. Key Biscayne is located in USDA Plant Hardiness Zone 11a.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 16.8 °C | 23.8 °C | 56.13 mm |
| February | 17.8 °C | 24.5 °C | 54.86 mm |
| March | 19.2 °C | 25.4 °C | 60.71 mm |
| April | 21.5 °C | 27 °C | 79.76 mm |
| May | 23.6 °C | 28.7 °C | 137.67 mm |
| June | 25.2 °C | 30.3 °C | 209.04 mm |
| July | 26 °C | 31.2 °C | 148.59 mm |
| August | 26.1 °C | 31.4 °C | 186.18 mm |
| September | 25.5 °C | 30.7 °C | 211.07 mm |
| October | 24 °C | 29.1 °C | 174.24 mm |
| November | 20.9 °C | 26.6 °C | 84.58 mm |
| December | 18.8 °C | 24.9 °C | 59.18 mm |
| Annual | 22.1 °C | 27.8 °C | 1462.01 mm |
| Average First Frost Date | No Frost |
| Average Last Frost Date | |
| Average Days With Frost | Frost Free |
| Plant Hardiness Zone | Zone 11a : 4.4°C to 7.2°C |
| Plant Hardiness Zone - 2012 | Zone 11a : 4.4°C to 7.2°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Am - Tropical Monsoon |