September Weather in Monticello, United States

Last updated: June 24, 2025

In September, the average temperature in Monticello, United States is a pleasant 25°C (77°F). However, temperatures can vary significantly, dipping to a minimum of 12°C (53°F) and soaring to a maximum of 36°C (98°F). Be prepared for some rain, as 103 mm (4.1 in) of precipitation typically falls over 9 days. Additionally, you can expect a high level of humidity at 82%, making it feel quite warm and sticky.

September Temperature in Monticello

In September in Monticello, the average temperature is 25°C (77°F). Maximum temperatures can reach 36°C (98°F), while minimums can drop as low as 12°C (53°F). Be sure to pack accordingly to enjoy the warm days and cooler nights!

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 25°C (77°F), with highs reaching up to 36°C (98°F) and lows dropping to around 12°C (53°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 103 mm (4.1 in) distributed over 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 103 mm (4.1 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 82%. With an average temperature of 25°C (77°F), this humidity feels like a warm, oppressive blanket enveloping you as you explore, making every step feel more laborious and prompting the need for frequent hydration breaks.

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 82%, 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	9°C (48°F)	106 mm (4.2 inches)	86%	moderate
February Weather	12°C (54°F)	127 mm (5.0 inches)	84%	high
March Weather	15°C (59°F)	88 mm (3.5 inches)	83%	very high
April Weather	18°C (65°F)	103 mm (4.0 inches)	81%	very high
May Weather	23°C (73°F)	95 mm (3.7 inches)	81%	extreme
June Weather	26°C (78°F)	119 mm (4.7 inches)	81%	extreme
July Weather	27°C (81°F)	116 mm (4.6 inches)	83%	extreme
August Weather	27°C (80°F)	123 mm (4.9 inches)	81%	very high
September Weather	25°C (77°F)	103 mm (4.1 inches)	82%	very high
October Weather	20°C (68°F)	107 mm (4.2 inches)	78%	very high
November Weather	13°C (55°F)	79 mm (3.1 inches)	86%	high
December Weather	10°C (51°F)	133 mm (5.2 inches)	89%	moderate