September Weather in Mount Washington, United States

Last updated: June 24, 2025

In September, the average temperature in Mount Washington, United States is a pleasant 22°C (72°F). However, be prepared for a range of temperatures; it can drop as low as 8°C (46°F) and soar to a scorching 36°C (97°F). You'll also encounter an average precipitation of 119 mm (4.7 in) spread over 9 days, contributing to a comfortable average humidity of 71%. Enjoy this vibrant climate!

September Temperature in Mount Washington

In September in Mount Washington, the average temperature is 22°C (72°F). Maximums can reach 36°C (97°F) and minimums can be as low as 8°C (46°F). It's a great time to visit for those who enjoy mild weather with occasional warm days.

September Weather in Mount Washington: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Mount Washington, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Mount Washington, September typically has an average temperature of 22°C (72°F), with highs reaching up to 36°C (97°F) and lows dropping to around 8°C (46°F).

Data source: Temperature data for Mount Washington generated using information from the Copernicus Climate Change Service.

September Precipitation in Mount Washington

In Mount Washington in September, the precipitation amount is 119 mm (4.7 in) occurring over a span of 9 days.

September Precipitation Trends in Mount Washington

The chart displays monthly precipitation patterns in Mount Washington, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Mount Washington, September typically receives around 119 mm (4.7 inches) of precipitation spread over approximately 9 days.

Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

September Humidity in Mount Washington

In Mount Washington in September humidity is 71%. With an average temperature of 22°C (72°F), this humidity feels like the air is thick and slightly stifling, making outdoor activities require frequent breaks to stay hydrated and cool.

September Average Humidity in Mount Washington

This chart illustrates the average monthly humidity levels in Mount Washington, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Mount Washington is approximately 71%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Mount Washington

In Mount Washington in September, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in Mount Washington.

Maximum UV Index Levels in Mount Washington for September

The chart shows the monthly maximum UV Index (UVI) for Mount Washington in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Mount Washington typically reaches 9, which falls under the very high exposure category.

Data source: Mount Washington September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

Extreme (11+): Avoid the sun, stay in shade.
Very High (8-10): Limit sun exposure.
High (6-7): Use SPF 30+ and protective clothing.
Moderate (3-5): Midday shade recommended.
Low (0-2): No protection needed.

How September Weather in Mount Washington Compares to Other Months

Weather in Mount Washington varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Mount Washington, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Mount Washington, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	2°C (36°F)	93 mm (3.7 inches)	87%	moderate
February Weather	5°C (41°F)	142 mm (5.6 inches)	86%	moderate
March Weather	9°C (48°F)	137 mm (5.4 inches)	86%	high
April Weather	13°C (56°F)	142 mm (5.6 inches)	82%	very high
May Weather	20°C (68°F)	121 mm (4.7 inches)	82%	very high
June Weather	24°C (75°F)	161 mm (6.3 inches)	83%	extreme
July Weather	26°C (79°F)	101 mm (4.0 inches)	80%	very high
August Weather	25°C (77°F)	95 mm (3.8 inches)	74%	very high
September Weather	22°C (72°F)	119 mm (4.7 inches)	71%	very high
October Weather	16°C (61°F)	102 mm (4.0 inches)	78%	high
November Weather	7°C (46°F)	88 mm (3.5 inches)	88%	moderate
December Weather	5°C (42°F)	115 mm (4.5 inches)	88%	moderate