September Weather in Hartford, United States

Last updated: June 24, 2025

In September, the average temperature in Hartford, United States hovers around 18°C (66°F), making it a pleasant time to visit. However, be prepared for a temperature range that can dip to a cool 3°C (38°F) and soar up to a warm 33°C (91°F). Expect about 102 mm (4.0 in) of precipitation spread over 9 days, complemented by an average humidity of 75%. Pack accordingly to enjoy all that this destination has to offer!

September Temperature in Hartford

In September in Hartford, the average temperature is 18°C (66°F). The maximum can reach 33°C (91°F), and the minimum can be as low as 3°C (38°F). This makes Hartford a great destination for travelers seeking mild weather with a chance for warmth during the day and cooler evenings.

September Weather in Hartford: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Hartford, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Hartford, September typically has an average temperature of 18°C (66°F), with highs reaching up to 33°C (91°F) and lows dropping to around 3°C (38°F).

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

September Precipitation in Hartford

In Hartford in September, the total precipitation amount is 102 mm (4.0 in) over a span of 9 days.

September Precipitation Trends in Hartford

The chart displays monthly precipitation patterns in Hartford, 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 Hartford, September typically receives around 102 mm (4.0 inches) of precipitation spread over approximately 9 days.

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

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

September Humidity in Hartford

In Hartford in September humidity is 75%. With an average temperature of 18°C (66°F), this humidity feels like traveling through a warm, damp sauna, where the air clings to your skin, making each step feel heavier and more laborious, and creating a unique atmosphere that both enlivens the senses and challenges your comfort level.

September Average Humidity in Hartford

This chart illustrates the average monthly humidity levels in Hartford, 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 Hartford is approximately 75%, 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 Hartford

In Hartford in September, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Hartford.

Maximum UV Index Levels in Hartford for September

The chart shows the monthly maximum UV Index (UVI) for Hartford 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 Hartford typically reaches 8, which falls under the very high exposure category.

Data source: Hartford 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 Hartford Compares to Other Months

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

This table compares monthly weather conditions in Hartford, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	-7°C (20°F)	20 mm (0.8 inches)	80%	low
February Weather	-7°C (20°F)	23 mm (0.9 inches)	84%	moderate
March Weather	2°C (35°F)	65 mm (2.5 inches)	75%	moderate
April Weather	7°C (45°F)	80 mm (3.2 inches)	79%	very high
May Weather	15°C (59°F)	127 mm (5.0 inches)	74%	very high
June Weather	23°C (73°F)	83 mm (3.3 inches)	81%	extreme
July Weather	24°C (76°F)	81 mm (3.2 inches)	82%	very high
August Weather	22°C (72°F)	95 mm (3.7 inches)	80%	very high
September Weather	18°C (66°F)	102 mm (4.0 inches)	75%	very high
October Weather	9°C (48°F)	77 mm (3.1 inches)	77%	moderate
November Weather	1°C (35°F)	24 mm (1.0 inches)	85%	moderate
December Weather	-3°C (26°F)	39 mm (1.5 inches)	83%	low