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September Weather in Monticello, United States

Last updated: June 24, 2025

In September, the average temperature in Monticello, United States hovers around 19°C (66°F). Expect to experience a range from a brisk minimum of 2°C (36°F) to a warm maximum of 33°C (92°F). With an average humidity of 79%, you'll want to prepare for some moisture in the air. Additionally, be ready for 118 mm (4.6 in) of precipitation spread over 10 days, making it wise to carry an umbrella on your adventures!

September Temperature in Monticello

In September in Monticello, the average temperature is 19°C (66°F). The maximum can reach 33°C (92°F) and the minimum can be as low as 2°C (36°F). This diverse climate makes Monticello an ideal destination for travelers looking to experience a range of temperatures and activities.

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 19°C (66°F), with highs reaching up to 33°C (92°F) and lows dropping to around 2°C (36°F).
JanFebMarAprMayJunJulAugSepOctNovDec222337476071757266523730
Data source: Temperature data for Monticello generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Monticello

In Monticello in September, the total precipitation amount is 118 mm (4.6 in) over a span 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 118 mm (4.6 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec55545997136124781061181134349
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Monticello

In Monticello in September humidity is 79%. With an average temperature of 19°C (66°F), this humidity feels like a warm embrace, making it feel much warmer than the actual temperature and creating a heavy, sticky atmosphere that can be a bit uncomfortable 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 79%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec85%85%85%85%78%80%78%76%79%83%88%82%
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 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 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 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec34689101098532
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.
 TemperaturePrecipitationHumidityUV
January Weather-6°C (22°F)55 mm (2.2 inches)85%moderate
February Weather-5°C (24°F)54 mm (2.1 inches)85%moderate
March Weather3°C (37°F)59 mm (2.3 inches)85%high
April Weather8°C (47°F)97 mm (3.8 inches)85%very high
May Weather16°C (60°F)136 mm (5.3 inches)78%very high
June Weather22°C (71°F)124 mm (4.9 inches)80%very high
July Weather24°C (75°F)78 mm (3.1 inches)78%very high
August Weather22°C (72°F)106 mm (4.2 inches)76%very high
September Weather19°C (66°F)118 mm (4.6 inches)79%very high
October Weather11°C (52°F)113 mm (4.5 inches)83%moderate
November Weather3°C (37°F)43 mm (1.7 inches)88%moderate
December Weather-1°C (30°F)49 mm (1.9 inches)81%low

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