September is one of the cooler months of the year in Clare, with average highs near 18.8°C and lows around 6.4°C (mean 12.6°C). It is a relatively wet time of year, averaging 42 mm of rainfall and 69% relative humidity across the period.
September is one of the cooler months of the year in Clare. Across 45 years of records, the warmest September in Clare was 2023 — when the month averaged 15.7°C — while the coldest was 1992 at 9.5°C. Typical September days reach 18.8°C with nights near 6.4°C. The long-term trend is warming, about 0.4°C per decade.
September is a relatively wet time of year in Clare, averaging 42 mm of rainfall. The wettest September on record was 2016 with 182 mm, while the driest was 2006 at 10 mm.
Relative humidity in Clare during September averages 69%. The most humid September was 2010 at 82%, and the least humid was 2023 at 57%.
September receives about 4.9 kWh/m²/day of solar energy in Clare. The sunniest September was 2023 at 5.7 kWh/m²/day, and the cloudiest was 2010 at 4.1.
Average wind speed in Clare during September is 3.2 m/s. The windiest September was 1996 at 4.1 m/s, while the calmest were 1995, 2004 and 2015 at 2.7 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 12.0°C | 12.2°C | 13.0°C | 12.6°C | 13.6°C | +1.6°C |
| Avg High | 18.2°C | 18.2°C | 19.2°C | 18.8°C | 20.1°C | +1.9°C |
| Avg Low | 5.8°C | 6.1°C | 6.8°C | 6.4°C | 7.1°C | +1.3°C |
| Avg Rain | 32 mm | 53 mm | 42 mm | 49 mm | 31 mm | 0 mm |
September temperatures in Clare have risen by about 1.8°C between 1981–1985 and 2021–2025.
September has ranged from a record low of -1.1°C (1995) to a record high of 32.1°C (2023).
Rainfall in September is a relatively wet time of year, averaging 42 mm, with a wettest year of 182 mm.
A quieter season to visit Clare
If your dates are flexible, the more temperate months of December and March tend to be the most comfortable for visiting Clare. That said, September — with days averaging 18.8°C and nights around 6.4°C (mean 12.6°C) and moderate rainfall (42 mm) — can still be rewarding for travellers who don't mind the cooler conditions, and often means fewer crowds.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 19.8°C | 13.4°C | 7.0°C | 28.7°C | 4.3°C | 22 mm | 68% | 3.2 m/s | 5.3 |
| 2024 | 20.3°C | 13.3°C | 6.2°C | 31.1°C | 1.4°C | 14 mm | 63% | 3.3 m/s | 5.2 |
| 2023 🔥 | 23.3°C | 15.7°C | 8.1°C | 32.1°C | 3.1°C | 12 mm | 57% | 2.8 m/s | 5.7 |
| 2022 | 17.1°C | 11.8°C | 6.5°C | 22.0°C | 2.3°C | 67 mm | 78% | 3.1 m/s | 4.6 |
| 2021 | 19.7°C | 13.2°C | 6.8°C | 29.8°C | 3.1°C | 25 mm | 65% | 3.2 m/s | 5.2 |
| 2020 | 20.2°C | 14.1°C | 8.0°C | 28.3°C | 3.5°C | 49 mm | 65% | 3.6 m/s | 5 |
| 2019 | 20.1°C | 13.0°C | 5.9°C | 29.2°C | 0.8°C | 12 mm | 63% | 2.9 m/s | 5.4 |
| 2018 | 18.4°C | 11.6°C | 4.8°C | 25.0°C | 0.9°C | 17 mm | 64% | 2.8 m/s | 5.5 |
| 2017 | 18.4°C | 12.7°C | 7.0°C | 28.0°C | 2.6°C | 37 mm | 68% | 3.7 m/s | 5 |
| 2016 🌧️ | 15.4°C | 10.7°C | 5.9°C | 21.9°C | 2.0°C | 182 mm | 81% | 3.3 m/s | 4.3 |
| 2015 | 18.4°C | 12.1°C | 5.7°C | 25.9°C | 1.9°C | 38 mm | 69% | 2.7 m/s | 5.3 |
| 2014 | 19.5°C | 13.2°C | 6.8°C | 28.4°C | 2.9°C | 21 mm | 68% | 3.1 m/s | 5.2 |
| 2013 | 20.8°C | 15.0°C | 9.2°C | 26.7°C | 4.1°C | 47 mm | 71% | 3.4 m/s | 4.9 |
| 2012 | 20.0°C | 13.4°C | 6.7°C | 28.3°C | 3.6°C | 19 mm | 63% | 3.5 m/s | 5.1 |
| 2011 | 20.5°C | 13.6°C | 6.7°C | 30.9°C | 2.2°C | 28 mm | 62% | 3.4 m/s | 5.2 |
| 2010 | 16.2°C | 10.9°C | 5.5°C | 19.6°C | 1.7°C | 85 mm | 82% | 2.8 m/s | 4.1 |
| 2009 | 19.3°C | 13.1°C | 6.8°C | 28.9°C | 2.7°C | 72 mm | 68% | 3.6 m/s | 4.7 |
| 2008 | 19.8°C | 13.0°C | 6.1°C | 31.5°C | 2.4°C | 20 mm | 63% | 3.1 m/s | 5.4 |
| 2007 | 20.6°C | 13.9°C | 7.1°C | 30.9°C | 1.7°C | 23 mm | 60% | 3.6 m/s | 5.3 |
| 2006 | 21.0°C | 14.2°C | 7.4°C | 29.5°C | 3.1°C | 10 mm | 58% | 3.4 m/s | 5.4 |
| 2005 | 18.8°C | 12.8°C | 6.9°C | 26.3°C | 2.3°C | 60 mm | 70% | 3 m/s | 4.6 |
| 2004 | 18.0°C | 12.2°C | 6.4°C | 28.6°C | 0.3°C | 46 mm | 73% | 2.7 m/s | 4.7 |
| 2003 | 17.3°C | 11.7°C | 6.2°C | 26.7°C | 2.0°C | 35 mm | 72% | 3.9 m/s | 4.9 |
| 2002 | 19.3°C | 12.7°C | 6.1°C | 27.8°C | 0.7°C | 25 mm | 65% | 3.7 m/s | 4.8 |
| 2001 | 19.0°C | 13.0°C | 7.1°C | 28.5°C | 1.6°C | 84 mm | 73% | 3.1 m/s | 4.3 |
| 2000 | 19.1°C | 13.3°C | 7.5°C | 27.2°C | 4.0°C | 43 mm | 75% | 3.4 m/s | 4.8 |
| 1999 | 21.1°C | 14.5°C | 7.9°C | 30.9°C | 2.6°C | 53 mm | 64% | 3.1 m/s | 4.7 |
| 1998 | 19.9°C | 13.5°C | 7.1°C | 30.4°C | 3.3°C | 41 mm | 70% | 3.2 m/s | 4.8 |
| 1997 | 17.9°C | 12.3°C | 6.8°C | 22.7°C | 3.4°C | 87 mm | 74% | 2.8 m/s | 4.4 |
| 1996 | 16.5°C | 11.2°C | 5.9°C | 26.9°C | 0.7°C | 74 mm | 73% | 4.1 m/s | 4.9 |
| 1995 | 18.7°C | 12.3°C | 5.8°C | 24.7°C | -1.1°C | 33 mm | 67% | 2.7 m/s | 4.8 |
| 1994 | 17.6°C | 11.2°C | 4.8°C | 24.3°C | 0.6°C | 18 mm | 70% | 2.8 m/s | 5.2 |
| 1993 | 18.7°C | 12.4°C | 6.1°C | 26.5°C | 2.1°C | 59 mm | 69% | 2.8 m/s | 4.8 |
| 1992 ❄️ | 14.3°C | 9.5°C | 4.6°C | 18.8°C | 1.1°C | 101 mm | 82% | 2.9 m/s | 4.5 |
| 1991 | 18.5°C | 12.3°C | 6.0°C | 25.4°C | 1.4°C | 37 mm | 71% | 3.5 m/s | 5 |
| 1990 | 19.2°C | 12.6°C | 6.1°C | 30.2°C | 0.7°C | 28 mm | 68% | 3.1 m/s | 5.1 |
| 1989 | 17.5°C | 11.6°C | 5.8°C | 26.5°C | 1.3°C | 30 mm | 73% | 3.2 m/s | 5.1 |
| 1988 | 19.9°C | 13.4°C | 7.0°C | 29.0°C | 2.0°C | 35 mm | 61% | 3.5 m/s | 5.2 |
| 1987 | 19.6°C | 12.9°C | 6.1°C | 31.2°C | 1.1°C | 20 mm | 68% | 2.8 m/s | 4.9 |
| 1986 | 16.9°C | 11.3°C | 5.6°C | 23.7°C | 0.5°C | 45 mm | 77% | 3.2 m/s | 4.9 |
| 1985 | 17.1°C | 10.9°C | 4.8°C | 23.6°C | 0.5°C | 28 mm | 70% | 3 m/s | 4.9 |
| 1984 | 15.3°C | 9.8°C | 4.4°C | 23.2°C | 1.2°C | 44 mm | 74% | 3.3 m/s | 4.7 |
| 1983 | 18.4°C | 12.0°C | 5.7°C | 26.6°C | 0.7°C | 49 mm | 72% | 3.4 m/s | — |
| 1982 | 18.8°C | 12.1°C | 5.4°C | 29.1°C | 1.3°C | 21 mm | 63% | 3.1 m/s | — |
| 1981 | 20.2°C | 13.7°C | 7.2°C | 29.8°C | 3.4°C | 16 mm | 68% | 3 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 18.8°C with lows near 6.4°C (mean 12.6°C), based on 45 years of NASA POWER data.
September averages 42 mm of rainfall in Clare, a relatively wet time of year. The wettest on record was 182 mm in 2016.
The hottest September reached 32.1°C in 2023. The coldest dipped to -1.1°C in 1995.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 1.8°C. Daytime highs moved from 18°C to 20°C and overnight lows from 5.5°C to 6.9°C over the same span.
September is one of the cooler months of the year in Clare and a relatively wet time of year, so plan for around 18.8°C daytime highs and 6.4°C at night.
Not quite — September is the 4th coolest month in Clare, averaging 12.6°C.
For September in Clare, pack warm layers and a jacket for chilly mornings, with typical highs of 18.8°C and lows of 6.4°C.
Relative humidity in September averages 69% — moderately humid.
Average wind speed in September is 3.2 m/s. The windiest September on record averaged 4.1 m/s (1996).
The wettest September on record was 2016 with 182 mm. On average, September sees 42 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 Clare 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.
