Back Bay boasts a year-around average temperature of 10.8°C, peaking at 23.0°C in July, its warmest month, and dipping to an average low of -1.7°C in January, the coolest. Rainfall averages at 92.6mm annually, with March seeing the heaviest showers and February being the driest month.
Month | Temperature (Celcius) | Rainfall (mm) |
| January | -1.7 | 85.3 |
| February | -0.2 | 82.5 |
| March | 3.5 | 109.7 |
| April | 8.9 | 95.0 |
| May | 14.4 | 88.6 |
| June | 19.8 | 93.5 |
| July | 23.0 | 87.1 |
| August | 22.3 | 85.1 |
| September | 18.3 | 87.4 |
| October | 12.2 | 100.1 |
| November | 7.1 | 101.3 |
| December | 1.5 | 96.0 |