September is one of the warmer months of the year in Larne, with average highs near 14.8°C and lows around 11.9°C (mean 13.4°C). It is about average for rainfall, averaging 95 mm of rainfall and 86% relative humidity across the period.
September is one of the warmer months of the year in Larne. Across 45 years of records, the warmest September in Larne was 2023 — when the month averaged 15°C — while the coldest was 1986 at 11.6°C. Typical September days reach 14.8°C with nights near 11.9°C. The long-term trend is warming, about 0.3°C per decade.
September is about average for rainfall in Larne, averaging 95 mm of rainfall. The wettest September on record was 1981 with 186 mm, while the driest was 2014 at 11 mm.
Relative humidity in Larne during September averages 86%. The most humid September was 1985 at 89%, and the least humid were 1986 and 1990 at 82%.
September receives about 2.8 kWh/m²/day of solar energy in Larne. The sunniest Septembers were 1991 and 2015 at 3.2 kWh/m²/day, and the cloudiest was 1985 at 2.3.
Average wind speed in Larne during September is 5.3 m/s. The windiest September was 1983 at 6.6 m/s, while the calmest was 2014 at 3.5 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 12.7°C | 13.1°C | 13.7°C | 13.3°C | 14.1°C | +1.4°C |
| Avg High | 14.1°C | 14.6°C | 15.1°C | 14.8°C | 15.7°C | +1.6°C |
| Avg Low | 11.2°C | 11.7°C | 12.3°C | 11.9°C | 12.6°C | +1.4°C |
| Avg Rain | 113 mm | 80 mm | 90 mm | 92 mm | 103 mm | -10 mm |
September temperatures in Larne have risen by about 1.3°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 7.7°C (2007) to a record high of 21.2°C (2023).
Rainfall in September is about average for rainfall, averaging 95 mm, with a wettest year of 186 mm.
One of the best times to visit Larne
September is one of the best times to visit Larne. Expect days averaging 14.8°C and nights around 11.9°C (mean 13.4°C) — warmer than Larne's yearly average — with higher rainfall (95 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 | 15.3°C | 13.8°C | 12.3°C | 17.1°C | 10.1°C | 104 mm | 84% | 5.8 m/s | 2.8 |
| 2024 | 14.9°C | 13.3°C | 11.7°C | 19.4°C | 9.7°C | 61 mm | 85% | 5.3 m/s | 2.9 |
| 2023 🔥 | 16.8°C | 15.0°C | 13.3°C | 21.2°C | 10.7°C | 153 mm | 87% | 5.1 m/s | 2.8 |
| 2022 | 15.7°C | 14.4°C | 13.2°C | 17.7°C | 10.9°C | 144 mm | 84% | 5.3 m/s | 3 |
| 2021 | 16.3°C | 14.7°C | 13.1°C | 18.8°C | 10.6°C | 71 mm | 88% | 3.9 m/s | 2.6 |
| 2020 | 15.0°C | 13.4°C | 11.9°C | 18.7°C | 8.7°C | 86 mm | 85% | 5.2 m/s | 2.8 |
| 2019 | 15.0°C | 13.7°C | 12.3°C | 17.1°C | 11.2°C | 110 mm | 86% | 5.2 m/s | 2.8 |
| 2018 | 14.4°C | 12.8°C | 11.2°C | 17.6°C | 8.1°C | 80 mm | 83% | 6.2 m/s | 2.8 |
| 2017 | 14.5°C | 13.2°C | 11.8°C | 16.9°C | 9.7°C | 134 mm | 86% | 5.8 m/s | 2.6 |
| 2016 | 15.8°C | 14.3°C | 12.7°C | 19.5°C | 10.0°C | 98 mm | 87% | 5.7 m/s | 2.7 |
| 2015 | 14.0°C | 12.6°C | 11.3°C | 15.9°C | 9.6°C | 44 mm | 86% | 5 m/s | 3.2 |
| 2014 | 15.5°C | 14.0°C | 12.5°C | 17.7°C | 9.9°C | 11 mm | 87% | 3.5 m/s | 3 |
| 2013 | 14.5°C | 13.0°C | 11.6°C | 17.6°C | 8.9°C | 90 mm | 86% | 5.4 m/s | 2.6 |
| 2012 | 14.1°C | 12.6°C | 11.2°C | 17.5°C | 9.2°C | 122 mm | 85% | 6.3 m/s | 2.8 |
| 2011 | 15.0°C | 13.5°C | 12.0°C | 17.3°C | 9.8°C | 122 mm | 87% | 6.5 m/s | 2.8 |
| 2010 | 15.0°C | 13.7°C | 12.4°C | 17.3°C | 8.5°C | 109 mm | 86% | 5.5 m/s | 2.9 |
| 2009 | 14.9°C | 13.4°C | 12.0°C | 16.8°C | 10.1°C | 47 mm | 86% | 5.3 m/s | 2.9 |
| 2008 | 14.6°C | 13.3°C | 12.0°C | 16.4°C | 10.5°C | 113 mm | 87% | 4.9 m/s | 2.5 |
| 2007 | 14.7°C | 13.2°C | 11.8°C | 17.0°C | 7.7°C | 57 mm | 86% | 5.4 m/s | 2.8 |
| 2006 | 16.1°C | 14.8°C | 13.5°C | 18.6°C | 11.9°C | 132 mm | 89% | 5.2 m/s | 2.8 |
| 2005 | 15.4°C | 13.9°C | 12.3°C | 18.3°C | 9.7°C | 74 mm | 87% | 5.8 m/s | 2.7 |
| 2004 | 15.0°C | 13.7°C | 12.5°C | 18.2°C | 10.8°C | 111 mm | 87% | 6.4 m/s | 2.9 |
| 2003 | 15.4°C | 13.9°C | 12.4°C | 18.2°C | 9.2°C | 79 mm | 85% | 4.4 m/s | 2.9 |
| 2002 | 15.1°C | 13.8°C | 12.5°C | 16.7°C | 10.7°C | 60 mm | 87% | 3.8 m/s | 2.9 |
| 2001 | 14.5°C | 13.1°C | 11.7°C | 17.2°C | 9.0°C | 63 mm | 86% | 5.7 m/s | 2.8 |
| 2000 | 15.3°C | 13.8°C | 12.4°C | 17.7°C | 9.8°C | 161 mm | 87% | 5.1 m/s | 2.4 |
| 1999 | 15.7°C | 14.2°C | 12.7°C | 19.1°C | 10.0°C | 164 mm | 87% | 5.4 m/s | 2.7 |
| 1998 | 15.0°C | 13.7°C | 12.4°C | 17.9°C | 9.5°C | 76 mm | 88% | 5.1 m/s | 3 |
| 1997 | 14.9°C | 13.4°C | 11.9°C | 17.4°C | 9.8°C | 63 mm | 85% | 5.4 m/s | 2.8 |
| 1996 | 15.0°C | 13.3°C | 11.6°C | 18.4°C | 10.1°C | 38 mm | 86% | 4.8 m/s | 2.9 |
| 1995 | 14.8°C | 13.4°C | 12.0°C | 16.8°C | 9.3°C | 79 mm | 85% | 5 m/s | 3.1 |
| 1994 | 13.7°C | 12.3°C | 10.9°C | 16.8°C | 8.9°C | 65 mm | 85% | 4.8 m/s | 2.9 |
| 1993 | 13.8°C | 12.4°C | 11.1°C | 16.2°C | 8.6°C | 88 mm | 84% | 5.3 m/s | 2.6 |
| 1992 | 13.7°C | 12.3°C | 11.0°C | 16.6°C | 8.8°C | 110 mm | 85% | 5.6 m/s | 2.7 |
| 1991 | 15.1°C | 13.4°C | 11.7°C | 19.3°C | 7.9°C | 63 mm | 84% | 4.9 m/s | 3.2 |
| 1990 | 14.0°C | 12.7°C | 11.3°C | 18.0°C | 8.8°C | 56 mm | 82% | 5.7 m/s | 2.7 |
| 1989 | 14.6°C | 13.0°C | 11.4°C | 17.6°C | 10.2°C | 70 mm | 84% | 5.3 m/s | 2.4 |
| 1988 | 13.8°C | 12.4°C | 11.1°C | 16.2°C | 8.6°C | 107 mm | 86% | 6.1 m/s | 2.5 |
| 1987 | 13.8°C | 12.3°C | 10.9°C | 16.0°C | 8.6°C | 104 mm | 85% | 5.8 m/s | 2.7 |
| 1986 ❄️ | 13.0°C | 11.6°C | 10.1°C | 16.4°C | 8.0°C | 20 mm | 82% | 4.7 m/s | 2.9 |
| 1985 | 14.6°C | 13.1°C | 11.6°C | 17.4°C | 9.1°C | 176 mm | 89% | 4.9 m/s | 2.3 |
| 1984 | 14.1°C | 12.8°C | 11.5°C | 17.7°C | 8.2°C | 120 mm | 83% | 5.4 m/s | 2.5 |
| 1983 | 14.0°C | 12.6°C | 11.1°C | 16.4°C | 8.8°C | 101 mm | 85% | 6.6 m/s | — |
| 1982 | 14.3°C | 12.6°C | 10.8°C | 17.0°C | 8.8°C | 134 mm | 85% | 5.8 m/s | — |
| 1981 🌧️ | 15.0°C | 13.6°C | 12.1°C | 18.4°C | 10.2°C | 186 mm | 86% | 5.8 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 14.8°C with lows near 11.9°C (mean 13.4°C), based on 45 years of NASA POWER data.
September averages 95 mm of rainfall in Larne, about average for rainfall. The wettest on record was 186 mm in 1981.
The hottest September reached 21.2°C in 2023. The coldest dipped to 7.7°C in 2007.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 1.3°C. Daytime highs moved from 14.4°C to 15.8°C and overnight lows from 11.4°C to 12.7°C over the same span.
September is one of the warmer months of the year in Larne and about average for rainfall, so plan for around 14.8°C daytime highs and 11.9°C at night.
Not quite — September is the 10th coolest month in Larne, averaging 13.4°C.
For September in Larne, pack light layers you can adjust through the day, with typical highs of 14.8°C and lows of 11.9°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 86% — quite humid.
Average wind speed in September is 5.3 m/s. The windiest September on record averaged 6.6 m/s (1983).
The wettest September on record was 1981 with 186 mm. On average, September sees 95 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 Larne 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.
