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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 21°C (70°F), with a minimum of 5°C (42°F) and a peak of 34°C (94°F). Expect 79 mm (3.1 in) of precipitation spread over 7 days, contributing to an average humidity level of 79%. Whether you’re exploring the town or enjoying the great outdoors, be prepared for some delightful weather!

September Temperature in Monticello

In September in Monticello, the average temperature is 21°C (70°F), with maximums reaching up to 34°C (94°F) and minimums dropping as low as 5°C (42°F). This makes it an ideal time for travelers who enjoy warm weather but should also be prepared 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 21°C (70°F), with highs reaching up to 34°C (94°F) and lows dropping to around 5°C (42°F).
JanFebMarAprMayJunJulAugSepOctNovDec293143526574777470574136
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 79 mm (3.1 in) distributed over a period of 7 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 79 mm (3.1 inches) of precipitation spread over approximately 7 days.
JanFebMarAprMayJunJulAugSepOctNovDec777611812414410592101791197454
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 21°C (70°F), this humidity feels like a warm embrace, making outdoor exploration a bit sticky but still enjoyable for travelers who appreciate the lush, vibrant atmosphere.

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.
JanFebMarAprMayJunJulAugSepOctNovDec84%82%84%83%80%83%82%83%79%79%88%87%
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.
JanFebMarAprMayJunJulAugSepOctNovDec356910111098643
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-2°C (29°F)77 mm (3.0 inches)84%moderate
February Weather0°C (32°F)76 mm (3.0 inches)82%moderate
March Weather6°C (43°F)118 mm (4.7 inches)84%high
April Weather11°C (52°F)124 mm (4.9 inches)83%very high
May Weather18°C (65°F)144 mm (5.7 inches)80%very high
June Weather24°C (75°F)105 mm (4.1 inches)83%extreme
July Weather25°C (78°F)92 mm (3.6 inches)82%very high
August Weather23°C (74°F)101 mm (4.0 inches)82%very high
September Weather21°C (70°F)79 mm (3.1 inches)79%very high
October Weather14°C (57°F)118 mm (4.7 inches)79%high
November Weather5°C (42°F)74 mm (2.9 inches)88%moderate
December Weather2°C (36°F)54 mm (2.1 inches)87%moderate

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