September Weather in Monticello, United States

Last updated: June 24, 2025

In Monticello, United States, the average temperature in September reaches a warm 25°C (78°F). However, be prepared for a range of temperatures, as it can drop to a chilly 11°C (53°F) or soar up to a scorching 38°C (100°F). Expect about 91 mm (3.6 in) of precipitation over 7 days, coupled with an average humidity level of 73%, making it an ideal time for outdoor adventures with the right preparations!

September Temperature in Monticello

In September in Monticello, the average temperature is 25°C (78°F), with maximums reaching 38°C (100°F) and minimums dropping as low as 11°C (53°F). This varied climate makes it an ideal time for travelers to enjoy both warm and cooler activities, so pack accordingly!

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 (78°F), with highs reaching up to 38°C (100°F) and lows dropping to around 11°C (53°F).
JanFebMarAprMayJunJulAugSepOctNovDec454959637380828177665350
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 91 mm (3.6 in) over a span 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 91 mm (3.6 inches) of precipitation spread over approximately 7 days.
JanFebMarAprMayJunJulAugSepOctNovDec115183179163148118971119215075142
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 73%. With an average temperature of 25°C (78°F), this humidity feels like stepping into a warm, heavy blanket that wraps around you, making travel feel sluggish and requiring regular breaks to stay refreshed.

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 73%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec84%83%80%82%83%80%80%75%73%76%84%88%
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.
JanFebMarAprMayJunJulAugSepOctNovDec47810111211119764
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 Weather7°C (46°F)115 mm (4.5 inches)84%moderate
February Weather9°C (49°F)183 mm (7.2 inches)83%high
March Weather15°C (59°F)179 mm (7.1 inches)80%very high
April Weather17°C (63°F)163 mm (6.4 inches)82%very high
May Weather23°C (73°F)147 mm (5.8 inches)83%extreme
June Weather26°C (80°F)118 mm (4.6 inches)80%extreme
July Weather28°C (83°F)97 mm (3.8 inches)80%extreme
August Weather27°C (82°F)111 mm (4.4 inches)75%extreme
September Weather25°C (78°F)91 mm (3.6 inches)73%very high
October Weather19°C (67°F)150 mm (5.9 inches)76%high
November Weather12°C (53°F)75 mm (3.0 inches)84%high
December Weather10°C (50°F)142 mm (5.6 inches)88%moderate

Compare Monticello's Climate with Cities Worldwide