Last updated: June 24, 2025
In September, the average temperature in Brookline, United States is a pleasant 18°C (65°F). However, temperatures can vary significantly, with minimums dipping to 2°C (36°F) and maximums soaring to 33°C (92°F). Expect about 85 mm (3.3 in) of precipitation over approximately 8 days, contributing to an average humidity level of 71%. Embrace the mild climate and prepare for some occasional rain!
In September, in Brookline, the average temperature is 18°C (65°F). The maximum can reach 33°C (92°F), while the minimum can be as low as 2°C (36°F). This temperature range makes Brookline an ideal destination for travelers seeking both warm days and cool nights.
In Brookline in September, the precipitation amount is 85 mm (3.3 in) over the course of 8 days.
In Brookline in September humidity is 71%. With an average temperature of 18°C (65°F), this humidity feels like a warm embrace, making it a bit sticky and muggy, which can be slightly uncomfortable for traveling, especially if you're engaging in outdoor activities or exploring the city on foot.
In Brookline in September, the maximum UV index is 7, which corresponds to the high Exposure Category. This means that the time to burn is approximately 25 minutes. For more detailed information, you can check the Hourly UV Index in Brookline.
UV Risk Categories
Weather in Brookline varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Brookline, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -3°C (27°F) | 75 mm (2.9 inches) | 86% | moderate |
| February Weather | -1°C (30°F) | 88 mm (3.5 inches) | 84% | moderate |
| March Weather | 2°C (35°F) | 83 mm (3.3 inches) | 82% | moderate |
| April Weather | 8°C (47°F) | 132 mm (5.2 inches) | 80% | very high |
| May Weather | 14°C (58°F) | 86 mm (3.4 inches) | 72% | very high |
| June Weather | 20°C (68°F) | 89 mm (3.5 inches) | 72% | very high |
| July Weather | 23°C (73°F) | 150 mm (5.9 inches) | 67% | very high |
| August Weather | 22°C (72°F) | 97 mm (3.8 inches) | 66% | very high |
| September Weather | 18°C (65°F) | 85 mm (3.3 inches) | 71% | high |
| October Weather | 12°C (54°F) | 134 mm (5.3 inches) | 78% | high |
| November Weather | 4°C (40°F) | 103 mm (4.0 inches) | 84% | moderate |
| December Weather | -1°C (31°F) | 124 mm (4.9 inches) | 81% | low |