September Weather in Monticello, United States

Last updated: June 24, 2025

In Monticello, United States, the average temperature in September reaches a pleasant 22°C (72°F). However, be prepared for a range, as temperatures can dip to a cool 8°C (47°F) or rise to a sizzling 35°C (94°F). This month also sees 114 mm (4.5 in) of precipitation spread over 9 days, contributing to an average humidity level of 67%.

September Temperature in Monticello

In September in Monticello, the average temperature is 22°C (72°F). Maximums can reach 35°C (94°F) and minimums can drop as low as 8°C (47°F). It's a great time to visit for those who enjoy mild to warm weather with a chance for 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 22°C (72°F), with highs reaching up to 35°C (94°F) and lows dropping to around 8°C (47°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 the course of 9 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 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 Monticello

In Monticello in September humidity is 67%. With an average temperature of 22°C (72°F), this humidity feels like a warm embrace, creating a tropical ambiance that can be both refreshing and slightly stifling for traveling.

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 67%, 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 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 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 9, 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	4°C (39°F)	97 mm (3.8 inches)	88%	moderate
February Weather	7°C (44°F)	180 mm (7.1 inches)	88%	high
March Weather	10°C (51°F)	147 mm (5.8 inches)	87%	high
April Weather	14°C (58°F)	145 mm (5.7 inches)	84%	very high
May Weather	20°C (68°F)	128 mm (5.0 inches)	84%	extreme
June Weather	23°C (74°F)	140 mm (5.5 inches)	83%	extreme
July Weather	26°C (78°F)	104 mm (4.1 inches)	79%	extreme
August Weather	24°C (76°F)	129 mm (5.1 inches)	66%	very high
September Weather	22°C (72°F)	114 mm (4.5 inches)	67%	very high
October Weather	17°C (62°F)	127 mm (5.0 inches)	76%	high
November Weather	9°C (48°F)	74 mm (2.9 inches)	89%	moderate
December Weather	7°C (44°F)	136 mm (5.4 inches)	88%	moderate