September is one of the warmer months of the year in St. John's, with average highs near 14.6°C and lows around 11°C (mean 12.8°C). It is about average for rainfall, averaging 102 mm of rainfall and 87% relative humidity across the period.
September is one of the warmer months of the year in St. John's. Across 45 years of records, the warmest September in St. John's was 2022 — when the month averaged 14.9°C — while the coldest was 1991 at 11°C. Typical September days reach 14.6°C with nights near 11°C. The long-term trend is warming, about 0.4°C per decade.
September is about average for rainfall in St. John's, averaging 102 mm of rainfall. The wettest September on record was 2001 with 216 mm, while the driest was 2003 at 45 mm.
Relative humidity in St. John's during September averages 87%. The most humid Septembers were 1991 and 1997 at 89%, and the least humid was 2018 at 84%.
September receives about 3.4 kWh/m²/day of solar energy in St. John's. The sunniest Septembers were 1988 and 2012 at 3.8 kWh/m²/day, and the cloudiest were 1991, 1997 and 1998 at 3.
Average wind speed in St. John's during September is 4.5 m/s. The windiest September was 2022 at 5.4 m/s, while the calmest was 2025 at 3.7 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 12.3°C | 12.3°C | 13.0°C | 13.0°C | 14.0°C | +1.7°C |
| Avg High | 14.0°C | 14.1°C | 14.8°C | 14.9°C | 15.8°C | +1.8°C |
| Avg Low | 10.5°C | 10.6°C | 11.1°C | 11.2°C | 12.4°C | +1.9°C |
| Avg Rain | 116 mm | 105 mm | 109 mm | 100 mm | 72 mm | -43 mm |
September temperatures in St. John's have risen by about 1.6°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 4.5°C (1986) to a record high of 24°C (2001).
Rainfall in September is about average for rainfall, averaging 102 mm, with a wettest year of 216 mm.
One of the best times to visit St. John's
September is one of the best times to visit St. John's. Expect days averaging 14.6°C and nights around 11°C (mean 12.8°C) — warmer than St. John's's yearly average — with higher rainfall (102 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 | 15.0°C | 13.0°C | 11.1°C | 19.0°C | 8.3°C | 53 mm | 87% | 3.7 m/s | 3.6 |
| 2024 | 15.8°C | 14.3°C | 12.8°C | 20.8°C | 9.8°C | 66 mm | 88% | 4.5 m/s | 3.4 |
| 2023 | 15.9°C | 14.2°C | 12.5°C | 21.9°C | 7.3°C | 62 mm | 88% | 4.1 m/s | 3.3 |
| 2022 🔥 | 16.2°C | 14.9°C | 13.7°C | 23.3°C | 9.7°C | 102 mm | 88% | 5.4 m/s | 3.2 |
| 2021 | 15.7°C | 13.7°C | 11.8°C | 20.1°C | 8.1°C | 70 mm | 88% | 4.3 m/s | 3.6 |
| 2020 | 15.9°C | 14.1°C | 12.3°C | 20.8°C | 8.4°C | 82 mm | 84% | 4.7 m/s | 3.7 |
| 2019 | 14.1°C | 12.3°C | 10.5°C | 19.1°C | 6.8°C | 83 mm | 86% | 4.8 m/s | 3.4 |
| 2018 | 14.2°C | 12.4°C | 10.6°C | 20.0°C | 5.6°C | 92 mm | 84% | 4.2 m/s | 3.4 |
| 2017 | 15.0°C | 13.2°C | 11.4°C | 19.2°C | 5.9°C | 161 mm | 87% | 4.4 m/s | 3.2 |
| 2016 | 13.7°C | 11.8°C | 9.9°C | 19.5°C | 6.3°C | 104 mm | 86% | 4.6 m/s | 3.4 |
| 2015 | 15.0°C | 12.8°C | 10.6°C | 19.3°C | 5.2°C | 109 mm | 87% | 4.6 m/s | 3.2 |
| 2014 | 15.2°C | 13.3°C | 11.5°C | 18.7°C | 6.3°C | 65 mm | 85% | 4.7 m/s | 3.7 |
| 2013 | 16.0°C | 14.1°C | 12.2°C | 19.1°C | 7.5°C | 114 mm | 89% | 4.7 m/s | 3.2 |
| 2012 | 16.1°C | 14.5°C | 12.8°C | 20.2°C | 10.3°C | 87 mm | 87% | 4.4 m/s | 3.8 |
| 2011 | 14.8°C | 12.9°C | 10.9°C | 19.8°C | 7.1°C | 49 mm | 88% | 4.4 m/s | 3.6 |
| 2010 | 14.8°C | 13.1°C | 11.4°C | 19.8°C | 5.1°C | 135 mm | 88% | 5 m/s | 3.1 |
| 2009 | 13.2°C | 11.2°C | 9.3°C | 16.7°C | 5.2°C | 99 mm | 86% | 5 m/s | 3.6 |
| 2008 | 15.0°C | 13.4°C | 11.7°C | 19.9°C | 6.7°C | 77 mm | 86% | 4.1 m/s | 3.5 |
| 2007 | 14.8°C | 12.9°C | 11.0°C | 18.0°C | 8.2°C | 68 mm | 84% | 4.5 m/s | 3.5 |
| 2006 | 15.4°C | 13.7°C | 12.0°C | 18.6°C | 9.0°C | 99 mm | 86% | 4.5 m/s | 3.3 |
| 2005 | 15.2°C | 13.6°C | 11.9°C | 19.7°C | 8.5°C | 102 mm | 87% | 5 m/s | 3.2 |
| 2004 | 14.0°C | 12.3°C | 10.6°C | 17.7°C | 7.5°C | 162 mm | 87% | 4.6 m/s | 3.2 |
| 2003 | 16.1°C | 14.3°C | 12.5°C | 21.2°C | 8.7°C | 45 mm | 87% | 4 m/s | 3.7 |
| 2002 | 14.0°C | 11.8°C | 9.7°C | 17.3°C | 6.0°C | 126 mm | 86% | 4.7 m/s | 3.4 |
| 2001 🌧️ | 15.1°C | 13.2°C | 11.2°C | 24.0°C | 6.8°C | 216 mm | 87% | 4.2 m/s | 3.5 |
| 2000 | 15.1°C | 13.2°C | 11.3°C | 17.9°C | 6.0°C | 92 mm | 85% | 4.5 m/s | 3.5 |
| 1999 | 16.1°C | 14.2°C | 12.3°C | 20.8°C | 8.0°C | 53 mm | 86% | 4.7 m/s | 3.6 |
| 1998 | 13.6°C | 12.1°C | 10.5°C | 17.2°C | 8.0°C | 157 mm | 89% | 4.6 m/s | 3 |
| 1997 | 14.1°C | 12.4°C | 10.7°C | 17.2°C | 6.1°C | 108 mm | 89% | 4.7 m/s | 3 |
| 1996 | 13.2°C | 11.4°C | 9.6°C | 17.9°C | 6.0°C | 125 mm | 86% | 5 m/s | 3.3 |
| 1995 | 13.3°C | 11.5°C | 9.8°C | 18.2°C | 5.9°C | 73 mm | 87% | 4.3 m/s | 3.4 |
| 1994 | 14.6°C | 13.1°C | 11.5°C | 18.3°C | 8.5°C | 140 mm | 86% | 4.8 m/s | 3.3 |
| 1993 | 14.0°C | 12.2°C | 10.4°C | 17.5°C | 8.1°C | 112 mm | 87% | 4.5 m/s | 3.3 |
| 1992 | 14.1°C | 12.2°C | 10.3°C | 17.2°C | 7.6°C | 91 mm | 88% | 3.8 m/s | 3.3 |
| 1991 ❄️ | 12.8°C | 11.0°C | 9.2°C | 18.7°C | 6.5°C | 93 mm | 89% | 4.2 m/s | 3 |
| 1990 | 15.1°C | 13.2°C | 11.4°C | 18.3°C | 8.2°C | 96 mm | 86% | 3.9 m/s | 3.6 |
| 1989 | 15.0°C | 12.8°C | 10.6°C | 18.7°C | 5.1°C | 94 mm | 85% | 4.5 m/s | 3.5 |
| 1988 | 14.3°C | 12.4°C | 10.4°C | 18.3°C | 6.0°C | 69 mm | 84% | 5 m/s | 3.8 |
| 1987 | 13.6°C | 12.0°C | 10.3°C | 16.6°C | 6.5°C | 95 mm | 85% | 4.6 m/s | 3.3 |
| 1986 | 12.4°C | 11.1°C | 9.8°C | 16.4°C | 4.5°C | 102 mm | 85% | 4.3 m/s | 3.3 |
| 1985 | 13.2°C | 11.5°C | 9.8°C | 17.2°C | 7.7°C | 74 mm | 85% | 3.8 m/s | 3.6 |
| 1984 | 14.7°C | 12.6°C | 10.5°C | 18.9°C | 7.1°C | 132 mm | 85% | 4.9 m/s | 3.6 |
| 1983 | 13.9°C | 12.2°C | 10.4°C | 19.6°C | 7.2°C | 155 mm | 88% | 4.4 m/s | — |
| 1982 | 14.7°C | 12.7°C | 10.7°C | 18.2°C | 5.5°C | 156 mm | 87% | 4.5 m/s | — |
| 1981 | 14.3°C | 13.0°C | 11.8°C | 17.7°C | 7.6°C | 164 mm | 87% | 5.1 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 14.6°C with lows near 11°C (mean 12.8°C), based on 45 years of NASA POWER data.
September averages 102 mm of rainfall in St. John's, about average for rainfall. The wettest on record was 216 mm in 2001.
The hottest September reached 24°C in 2001. The coldest dipped to 4.5°C in 1986.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 1.6°C. Daytime highs moved from 14.2°C to 15.7°C and overnight lows from 10.6°C to 12.4°C over the same span.
September is one of the warmer months of the year in St. John's and about average for rainfall, so plan for around 14.6°C daytime highs and 11°C at night.
Not quite — September is the 10th coolest month in St. John's, averaging 12.8°C.
For September in St. John's, pack light layers you can adjust through the day, with typical highs of 14.6°C and lows of 11°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 87% — quite humid.
Average wind speed in September is 4.5 m/s. The windiest September on record averaged 5.4 m/s (2022).
The wettest September on record was 2001 with 216 mm. On average, September sees 102 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 St. John's 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.
