nomadseason

September Weather in Rockville, United States

Last updated: June 24, 2025

In September, the average temperature in Rockville, United States hovers around 21°C (71°F), making it a pleasant time to visit. Be prepared for temperatures that can range from a cool 6°C (43°F) to a warm 34°C (93°F). During this month, expect an average precipitation of 64 mm (2.5 in) over 6 days, contributing to a comfortable average humidity level of 69%.

September Temperature in Rockville

In September in Rockville, the average temperature is 21°C (71°F). The maximum can reach 34°C (93°F), while the minimum can dip to as low as 6°C (43°F). This diverse range makes it essential for travelers to pack both light clothing for warm days and layers for cooler evenings.

September Weather in Rockville: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Rockville, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Rockville, September typically has an average temperature of 21°C (71°F), with highs reaching up to 34°C (93°F) and lows dropping to around 6°C (43°F).
JanFebMarAprMayJunJulAugSepOctNovDec303343526574777570584236
Data source: Temperature data for Rockville generated using information from the Copernicus Climate Change Service.
Choose your preferred temperature unit
The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Rockville

In Rockville in September, the total precipitation amount is 64 mm (2.5 in) during a span of 6 days.

September Precipitation Trends in Rockville

The chart displays monthly precipitation patterns in Rockville, 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 Rockville, September typically receives around 64 mm (2.5 inches) of precipitation spread over approximately 6 days.
JanFebMarAprMayJunJulAugSepOctNovDec8488122106140113103100651188775
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

September Humidity in Rockville

In Rockville in September humidity is 69%. With an average temperature of 21°C (71°F), this humidity feels like a warm embrace, creating a tropical atmosphere that can make outdoor activities feel slightly sticky, yet invigorating for travelers who are ready to embrace the local culture and explore.

September Average Humidity in Rockville

This chart illustrates the average monthly humidity levels in Rockville, 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 Rockville is approximately 69%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec87%85%86%84%79%82%79%70%69%76%88%87%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Rockville

In Rockville 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 Rockville.

Maximum UV Index Levels in Rockville for September

The chart shows the monthly maximum UV Index (UVI) for Rockville 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 Rockville typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356910111098643
Data source: Rockville 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 Rockville Compares to Other Months

Weather in Rockville varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Rockville, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Rockville, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-1°C (30°F)84 mm (3.3 inches)87%moderate
February Weather1°C (33°F)88 mm (3.5 inches)85%moderate
March Weather6°C (43°F)122 mm (4.8 inches)86%high
April Weather11°C (53°F)106 mm (4.2 inches)84%very high
May Weather18°C (65°F)140 mm (5.5 inches)79%very high
June Weather24°C (75°F)113 mm (4.5 inches)82%extreme
July Weather25°C (78°F)103 mm (4.1 inches)79%very high
August Weather24°C (75°F)100 mm (3.9 inches)70%very high
September Weather21°C (71°F)64 mm (2.5 inches)69%very high
October Weather14°C (58°F)118 mm (4.6 inches)76%high
November Weather5°C (42°F)87 mm (3.4 inches)88%moderate
December Weather2°C (36°F)75 mm (3.0 inches)87%moderate

Compare Rockville's Climate with Cities Worldwide