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September Weather in Monticello, United States

Last updated: June 24, 2025

In Monticello, United States, the average temperature in September hovers around 14°C (58°F). While you might experience a chilly minimum of -3°C (27°F), the mercury can soar to a maximum of 32°C (90°F). Expect 98 mm (3.8 in) of precipitation spread over 10 days, contributing to a notably high average humidity of 85%. Prepare accordingly for a mix of refreshingly cool and warm days!

September Temperature in Monticello

In September in Monticello, the average temperature is 14°C (58°F). Maximums can reach 32°C (90°F), while minimums can drop as low as -3°C (27°F). Therefore, it's wise to pack for both warm and chilly weather during your travels.

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 14°C (58°F), with highs reaching up to 32°C (90°F) and lows dropping to around -3°C (27°F).
JanFebMarAprMayJunJulAugSepOctNovDec161826395262676658463321
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 precipitation amount is 98 mm (3.8 in) spread 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 98 mm (3.8 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec948377110108951018898118117113
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 85%. With an average temperature of 14°C (58°F), this humidity feels like a thick blanket wrapping around you, making even short walks feel heavy and exhausting 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 85%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec93%92%90%87%82%77%82%83%85%87%88%90%
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 7, which corresponds to the high Exposure Category. This means that the time to burn is approximately 25 minutes. 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 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec2357810887532
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-9°C (16°F)94 mm (3.7 inches)93%low
February Weather-8°C (18°F)83 mm (3.3 inches)92%moderate
March Weather-3°C (26°F)77 mm (3.0 inches)90%moderate
April Weather4°C (40°F)109 mm (4.3 inches)87%high
May Weather11°C (52°F)108 mm (4.2 inches)82%very high
June Weather16°C (62°F)95 mm (3.8 inches)77%very high
July Weather20°C (68°F)101 mm (4.0 inches)81%very high
August Weather19°C (66°F)88 mm (3.5 inches)83%very high
September Weather14°C (58°F)98 mm (3.8 inches)85%high
October Weather8°C (47°F)118 mm (4.6 inches)87%moderate
November Weather0°C (33°F)117 mm (4.6 inches)87%moderate
December Weather-6°C (21°F)113 mm (4.4 inches)90%low

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