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September Weather in Markham, United States

Last updated: June 24, 2025

In September, the average temperature in Markham, United States is a pleasant 20°C (68°F). However, be prepared for temperature variations, as it can dip to a cool 4°C (39°F) or soar to a warm 34°C (94°F). Expect around 80 mm (3.1 in) of precipitation spread over 9 days, and a relatively high average humidity of 80%.

September Temperature in Markham

In September in Markham, the average temperature is 20°C (68°F). Maximum temperatures can reach 34°C (94°F), while minimums can dip as low as 4°C (39°F). It's a great time to visit for a mix of warm days and cooler evenings, perfect for outdoor adventures and exploration.

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

The chart illustrates September temperature patterns in Markham, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Markham, September typically has an average temperature of 20°C (68°F), with highs reaching up to 34°C (94°F) and lows dropping to around 4°C (39°F).
JanFebMarAprMayJunJulAugSepOctNovDec272840496172757368554034
Data source: Temperature data for Markham 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 Markham

In Markham in September, the precipitation amount is 80 mm (3.1 in) spread over 9 days.

September Precipitation Trends in Markham

The chart displays monthly precipitation patterns in Markham, 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 Markham, September typically receives around 80 mm (3.1 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec66699612216314311492801396357
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Markham

In Markham in September, humidity is 80%. With an average temperature of 20°C (68°F), this humidity feels like traveling through a warm, dense blanket that clings to your skin, making you feel both sticky and lethargic as you explore the sights.

September Average Humidity in Markham

This chart illustrates the average monthly humidity levels in Markham, 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 Markham is approximately 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec82%83%84%85%79%82%80%81%80%82%88%84%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Markham

In Markham 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 Markham.

Maximum UV Index Levels in Markham for September

The chart shows the monthly maximum UV Index (UVI) for Markham 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 Markham typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec34689101098642
Data source: Markham 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 Markham Compares to Other Months

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

This table compares monthly weather conditions in Markham, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-3°C (27°F)66 mm (2.6 inches)82%moderate
February Weather-2°C (29°F)69 mm (2.7 inches)83%moderate
March Weather4°C (40°F)96 mm (3.8 inches)84%high
April Weather9°C (49°F)122 mm (4.8 inches)85%very high
May Weather16°C (61°F)163 mm (6.4 inches)79%very high
June Weather22°C (72°F)143 mm (5.6 inches)82%very high
July Weather24°C (76°F)114 mm (4.5 inches)80%very high
August Weather23°C (73°F)92 mm (3.6 inches)81%very high
September Weather20°C (68°F)80 mm (3.1 inches)80%very high
October Weather13°C (55°F)139 mm (5.5 inches)82%high
November Weather4°C (40°F)63 mm (2.5 inches)88%moderate
December Weather1°C (34°F)57 mm (2.2 inches)84%low

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