September Weather in Monticello, United States

Last updated: June 24, 2025

In September, the average temperature in Monticello, United States reaches a warm 26°C (79°F), with minimums dipping to 11°C (51°F) and soaring to a maximum of 38°C (101°F). Expect 114 mm (4.5 in) of precipitation spread over about 10 days, contributing to an average humidity of 79%. Ideal for those who enjoy a tropical atmosphere, but don’t forget your umbrella!

September Temperature in Monticello

In September in Monticello, the average temperature is 26°C (79°F), with maximums reaching 38°C (101°F) and minimums dropping as low as 11°C (51°F). This pleasant weather makes Monticello an ideal destination for travelers looking to enjoy both warm days and cooler evenings.

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

The chart illustrates September temperature patterns in Monticello, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Monticello, September typically has an average temperature of 26°C (79°F), with highs reaching up to 38°C (101°F) and lows dropping to around 11°C (51°F).

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

September Precipitation in Monticello

In Monticello in September, the precipitation amount is 114 mm (4.5 in) over a period of 10 days.

September Precipitation Trends in Monticello

The chart displays monthly precipitation patterns in Monticello, 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 Monticello, September typically receives around 114 mm (4.5 inches) of precipitation spread over approximately 10 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 Monticello

In Monticello in September humidity is 79%. With an average temperature of 26°C (79°F), this humidity feels like a warm, sticky embrace that can make outdoor activities feel exhausting. Travelers should be prepared for a heavy air that clings to the skin, making hydration essential while navigating the sights and sounds of the city.

September Average Humidity in Monticello

This chart illustrates the average monthly humidity levels in Monticello, 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 Monticello is approximately 79%, 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 Monticello

In Monticello in September, the maximum UV index reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more detailed information, you can check the Hourly UV Index in Monticello.

Maximum UV Index Levels in Monticello for September

The chart shows the monthly maximum UV Index (UVI) for Monticello 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 Monticello typically reaches 10, which falls under the very high exposure category.

Data source: Monticello 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 Monticello Compares to Other Months

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

This table compares monthly weather conditions in Monticello, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	10°C (50°F)	116 mm (4.6 inches)	83%	moderate
February Weather	13°C (56°F)	118 mm (4.6 inches)	83%	high
March Weather	16°C (62°F)	117 mm (4.6 inches)	80%	very high
April Weather	19°C (66°F)	143 mm (5.6 inches)	81%	extreme
May Weather	23°C (74°F)	160 mm (6.3 inches)	81%	extreme
June Weather	26°C (79°F)	158 mm (6.2 inches)	78%	extreme
July Weather	27°C (81°F)	133 mm (5.2 inches)	79%	extreme
August Weather	27°C (81°F)	170 mm (6.7 inches)	79%	extreme
September Weather	26°C (79°F)	114 mm (4.5 inches)	79%	very high
October Weather	21°C (70°F)	98 mm (3.9 inches)	77%	very high
November Weather	14°C (57°F)	83 mm (3.3 inches)	85%	high
December Weather	12°C (53°F)	141 mm (5.6 inches)	88%	moderate