September is one of the warmer months of the year in Markham, with average highs near 22.2°C and lows around 11.5°C (mean 16.9°C). It is about average for rainfall, averaging 64 mm of rainfall and 71% relative humidity across the period.
September is one of the warmer months of the year in Markham. Across 45 years of records, the warmest September in Markham was 2015 — when the month averaged 19.8°C — while the coldest was 1993 at 13.7°C. Typical September days reach 22.2°C with nights near 11.5°C. The long-term trend is warming, about 0.9°C per decade.
September is about average for rainfall in Markham, averaging 64 mm of rainfall. The wettest September on record was 1986 with 136 mm, while the driest was 2023 at 17 mm.
Relative humidity in Markham during September averages 71%. The most humid September was 1981 at 80%, and the least humid was 2025 at 65%.
September receives about 4.1 kWh/m²/day of solar energy in Markham. The sunniest September was 2005 at 4.7 kWh/m²/day, and the cloudiest were 1993 and 2006 at 3.2.
Average wind speed in Markham during September is 2.7 m/s. The windiest September was 2010 at 3.3 m/s, while the calmest were 2017 and 2025 at 2.1 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 15.6°C | 15.7°C | 17.3°C | 17.9°C | 18.4°C | +2.8°C |
| Avg High | 21.0°C | 21.1°C | 22.7°C | 23.1°C | 23.8°C | +2.8°C |
| Avg Low | 10.3°C | 10.3°C | 11.8°C | 12.6°C | 13.0°C | +2.7°C |
| Avg Rain | 75 mm | 67 mm | 62 mm | 61 mm | 48 mm | -27 mm |
September temperatures in Markham have risen by about 3.1°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 0.1°C (1989) to a record high of 34°C (2023).
Rainfall in September is about average for rainfall, averaging 64 mm, with a wettest year of 136 mm.
One of the best times to visit Markham
September is one of the best times to visit Markham. Expect days averaging 22.2°C and nights around 11.5°C (mean 16.9°C) — warmer than Markham's yearly average — with moderate rainfall (64 mm), so conditions are generally comfortable for sightseeing and outdoor plans.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 24.5°C | 18.8°C | 13.1°C | 28.2°C | 8.0°C | 45 mm | 65% | 2.1 m/s | 4.5 |
| 2024 | 25.0°C | 19.5°C | 14.1°C | 29.1°C | 8.5°C | 60 mm | 70% | 2.4 m/s | 4.3 |
| 2023 | 24.6°C | 19.0°C | 13.3°C | 34.0°C | 7.6°C | 17 mm | 68% | 2.3 m/s | 4.4 |
| 2022 | 23.1°C | 17.9°C | 12.7°C | 31.7°C | 5.7°C | 34 mm | 68% | 2.6 m/s | 3.9 |
| 2021 | 23.3°C | 18.2°C | 13.1°C | 27.2°C | 7.5°C | 96 mm | 70% | 3.2 m/s | 4.3 |
| 2020 | 22.5°C | 17.2°C | 12.0°C | 28.2°C | 4.8°C | 37 mm | 69% | 3 m/s | 4.2 |
| 2019 | 23.2°C | 18.0°C | 12.8°C | 29.5°C | 8.8°C | 48 mm | 73% | 2.8 m/s | 3.8 |
| 2018 | 24.0°C | 19.0°C | 14.1°C | 33.1°C | 7.7°C | 53 mm | 72% | 2.8 m/s | 3.9 |
| 2017 | 24.6°C | 19.0°C | 13.3°C | 33.1°C | 6.2°C | 42 mm | 69% | 2.1 m/s | 4.6 |
| 2016 | 24.7°C | 19.3°C | 14.0°C | 31.1°C | 7.5°C | 54 mm | 67% | 2.7 m/s | 4.4 |
| 2015 🔥 | 25.2°C | 19.8°C | 14.5°C | 33.0°C | 8.0°C | 68 mm | 70% | 2.5 m/s | 4.2 |
| 2014 | 22.0°C | 16.6°C | 11.3°C | 29.2°C | 4.7°C | 70 mm | 73% | 2.6 m/s | 4.1 |
| 2013 | 21.7°C | 16.3°C | 10.8°C | 32.8°C | 4.1°C | 66 mm | 72% | 2.7 m/s | 4.1 |
| 2012 | 21.6°C | 16.5°C | 11.4°C | 29.4°C | 6.0°C | 67 mm | 70% | 2.7 m/s | 4.2 |
| 2011 | 22.5°C | 17.7°C | 12.8°C | 30.7°C | 5.6°C | 69 mm | 73% | 2.6 m/s | 3.8 |
| 2010 | 21.3°C | 16.4°C | 11.5°C | 32.7°C | 7.2°C | 71 mm | 73% | 3.3 m/s | 3.6 |
| 2009 | 22.4°C | 17.1°C | 11.8°C | 26.7°C | 4.8°C | 43 mm | 70% | 2.6 m/s | 4.4 |
| 2008 | 22.3°C | 17.1°C | 11.9°C | 31.3°C | 7.9°C | 63 mm | 74% | 2.3 m/s | 4 |
| 2007 | 23.7°C | 18.0°C | 12.3°C | 32.7°C | 4.9°C | 52 mm | 68% | 2.7 m/s | 4.5 |
| 2006 | 20.3°C | 15.6°C | 10.9°C | 26.6°C | 4.1°C | 91 mm | 76% | 2.9 m/s | 3.2 |
| 2005 | 25.0°C | 19.1°C | 13.1°C | 31.5°C | 6.3°C | 61 mm | 68% | 3.1 m/s | 4.7 |
| 2004 | 24.0°C | 18.3°C | 12.5°C | 29.1°C | 6.1°C | 39 mm | 71% | 2.6 m/s | 4.6 |
| 2003 | 21.7°C | 16.5°C | 11.3°C | 28.0°C | 4.4°C | 69 mm | 72% | 2.9 m/s | 4.1 |
| 2002 | 25.1°C | 19.4°C | 13.6°C | 33.4°C | 9.0°C | 48 mm | 67% | 2.6 m/s | 4.6 |
| 2001 | 21.2°C | 15.9°C | 10.6°C | 29.3°C | 3.4°C | 70 mm | 71% | 2.8 m/s | 4.3 |
| 2000 | 21.0°C | 15.7°C | 10.4°C | 31.3°C | 0.8°C | 81 mm | 72% | 3 m/s | 4 |
| 1999 | 23.5°C | 17.8°C | 12.1°C | 31.8°C | 3.6°C | 82 mm | 67% | 2.7 m/s | 4.2 |
| 1998 | 23.6°C | 17.9°C | 12.2°C | 31.0°C | 5.8°C | 52 mm | 68% | 2.7 m/s | 4.3 |
| 1997 | 21.4°C | 16.0°C | 10.6°C | 27.5°C | 3.6°C | 53 mm | 71% | 3.1 m/s | 3.9 |
| 1996 | 21.0°C | 16.2°C | 11.4°C | 29.1°C | 3.7°C | 98 mm | 75% | 2.6 m/s | 3.4 |
| 1995 | 20.0°C | 14.3°C | 8.6°C | 28.5°C | 4.5°C | 47 mm | 68% | 2.6 m/s | 4.1 |
| 1994 | 21.5°C | 15.9°C | 10.3°C | 29.1°C | 5.9°C | 44 mm | 72% | 2.7 m/s | 3.9 |
| 1993 ❄️ | 18.7°C | 13.7°C | 8.7°C | 28.5°C | 0.1°C | 84 mm | 73% | 2.9 m/s | 3.2 |
| 1992 | 19.6°C | 14.5°C | 9.4°C | 26.4°C | 1.9°C | 91 mm | 77% | 3.1 m/s | 4.1 |
| 1991 | 20.7°C | 15.2°C | 9.8°C | 30.3°C | 0.9°C | 49 mm | 65% | 2.8 m/s | 4.2 |
| 1990 | 20.9°C | 15.5°C | 10.1°C | 28.5°C | 3.4°C | 69 mm | 72% | 2.8 m/s | 3.6 |
| 1989 | 21.6°C | 16.2°C | 10.7°C | 28.6°C | 0.1°C | 71 mm | 69% | 2.7 m/s | 4 |
| 1988 | 21.8°C | 15.9°C | 10.1°C | 28.5°C | 5.7°C | 49 mm | 68% | 3.2 m/s | 4.3 |
| 1987 | 21.5°C | 16.2°C | 10.9°C | 28.0°C | 5.8°C | 60 mm | 73% | 2.6 m/s | 3.7 |
| 1986 🌧️ | 19.7°C | 14.6°C | 9.5°C | 26.0°C | 3.6°C | 136 mm | 78% | 2.7 m/s | 3.6 |
| 1985 | 22.1°C | 16.6°C | 11.2°C | 29.4°C | 4.2°C | 51 mm | 73% | 2.6 m/s | 4.5 |
| 1984 | 19.6°C | 14.3°C | 8.9°C | 26.7°C | 2.9°C | 78 mm | 72% | 2.8 m/s | 4 |
| 1983 | 23.0°C | 17.2°C | 11.3°C | 32.2°C | 4.9°C | 48 mm | 66% | 2.8 m/s | — |
| 1982 | 20.7°C | 15.2°C | 9.8°C | 29.3°C | 4.1°C | 72 mm | 73% | 2.4 m/s | — |
| 1981 | 18.6°C | 14.5°C | 10.4°C | 26.8°C | 1.7°C | 112 mm | 80% | 2.8 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 22.2°C with lows near 11.5°C (mean 16.9°C), based on 45 years of NASA POWER data.
September averages 64 mm of rainfall in Markham, about average for rainfall. The wettest on record was 136 mm in 1986.
The hottest September reached 34°C in 2023. The coldest dipped to 0.1°C in 1989.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 3.1°C. Daytime highs moved from 20.8°C to 24.1°C and overnight lows from 10.3°C to 13.3°C over the same span.
September is one of the warmer months of the year in Markham and about average for rainfall, so plan for around 22.2°C daytime highs and 11.5°C at night.
Not quite — September is the 9th coolest month in Markham, averaging 16.9°C.
For September in Markham, pack light layers you can adjust through the day, with typical highs of 22.2°C and lows of 11.5°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 71% — moderately humid.
Average wind speed in September is 2.7 m/s. The windiest September on record averaged 3.3 m/s (2010).
The wettest September on record was 1986 with 136 mm. On average, September sees 64 mm.
All figures are derived from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite reanalysis, covering 1981–2025.
Explore how the weather in Markham behaves each September, based on 45 years of NASA POWER climate data from 1981 to 2025. This page breaks down average temperatures, rainfall, humidity, wind and solar radiation for September specifically, along with year-by-year records and how the month has changed over the decades.
