September is one of the warmer months of the year in Santa Ana, with average highs near 23.3°C and lows around 18.9°C (mean 21.1°C). It is one of the drier months, averaging 6 mm of rainfall and 74% relative humidity across the period.
September is one of the warmer months of the year in Santa Ana. Across 45 years of records, the warmest September in Santa Ana was 1984 — when the month averaged 24.5°C — while the coldest was 1999 at 18.8°C. Typical September days reach 23.3°C with nights near 18.9°C. The long-term September temperature trend is broadly flat.
September is one of the drier months in Santa Ana, averaging 6 mm of rainfall. The wettest September on record was 1983 with 46 mm, while the driest were 2008, 2009 and 2020, among others at 0 mm.
Relative humidity in Santa Ana during September averages 74%. The most humid September was 2023 at 81%, and the least humid was 1984 at 68%.
September receives about 5.8 kWh/m²/day of solar energy in Santa Ana. The sunniest September was 2014 at 6.3 kWh/m²/day, and the cloudiest was 2023 at 5.1.
Average wind speed in Santa Ana during September is 2.3 m/s. The windiest September was 1986 at 2.8 m/s, while the calmest was 2011 at 2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 21.3°C | 20.9°C | 20.6°C | 21.3°C | 21.5°C | +0.2°C |
| Avg High | 23.8°C | 23.1°C | 22.8°C | 23.5°C | 23.5°C | -0.3°C |
| Avg Low | 18.9°C | 18.8°C | 18.3°C | 19.1°C | 19.5°C | +0.6°C |
| Avg Rain | 15 mm | 2 mm | 3 mm | 4 mm | 6 mm | -9 mm |
September temperatures in Santa Ana have fallen by about 0.7°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 14.5°C (1999) to a record high of 35.8°C (1988).
Rainfall in September is one of the drier months, averaging 6 mm, with a wettest year of 46 mm.
One of the best times to visit Santa Ana
September is one of the best times to visit Santa Ana. Expect days averaging 23.3°C and nights around 18.9°C (mean 21.1°C) — warmer than Santa Ana's yearly average — with low rainfall (6 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 | 23.6°C | 21.7°C | 19.8°C | 27.3°C | 17.9°C | 10 mm | 80% | 2.6 m/s | 5.7 |
| 2024 | 22.5°C | 20.5°C | 18.6°C | 29.6°C | 15.7°C | 1 mm | 77% | 2.6 m/s | 5.8 |
| 2023 | 22.1°C | 20.5°C | 18.9°C | 25.8°C | 17.0°C | 2 mm | 81% | 2.6 m/s | 5.1 |
| 2022 | 25.5°C | 23.5°C | 21.5°C | 30.1°C | 17.7°C | 17 mm | 75% | 2.4 m/s | 5.7 |
| 2021 | 22.4°C | 20.2°C | 18.1°C | 27.8°C | 15.5°C | 3 mm | 76% | 2.2 m/s | 5.9 |
| 2020 | 25.0°C | 22.4°C | 19.9°C | 31.6°C | 17.0°C | 0 mm | 73% | 2.2 m/s | 5.9 |
| 2019 | 24.0°C | 21.8°C | 19.7°C | 27.6°C | 16.6°C | 1 mm | 76% | 2.5 m/s | 6 |
| 2018 | 22.1°C | 20.1°C | 18.0°C | 25.7°C | 16.3°C | 0 mm | 77% | 2.3 m/s | 6.1 |
| 2017 | 23.8°C | 21.7°C | 19.6°C | 30.0°C | 16.9°C | 5 mm | 76% | 2.6 m/s | 5.7 |
| 2016 | 23.5°C | 21.3°C | 19.0°C | 32.8°C | 16.4°C | 1 mm | 71% | 2.3 m/s | 5.9 |
| 2015 | 25.6°C | 23.5°C | 21.4°C | 30.3°C | 18.5°C | 32 mm | 75% | 2.1 m/s | 6 |
| 2014 | 25.0°C | 22.9°C | 20.7°C | 30.4°C | 18.3°C | 1 mm | 73% | 2.4 m/s | 6.3 |
| 2013 | 23.2°C | 21.0°C | 18.8°C | 27.9°C | 16.1°C | 0 mm | 73% | 2.3 m/s | 6.1 |
| 2012 | 24.5°C | 22.3°C | 20.1°C | 31.5°C | 16.8°C | 1 mm | 71% | 2.2 m/s | 6.1 |
| 2011 | 21.1°C | 19.0°C | 16.9°C | 29.4°C | 15.6°C | 1 mm | 78% | 2 m/s | 5.5 |
| 2010 | 21.7°C | 19.4°C | 17.1°C | 32.5°C | 15.0°C | 1 mm | 73% | 2.2 m/s | 5.9 |
| 2009 | 24.1°C | 21.7°C | 19.2°C | 32.4°C | 17.1°C | 0 mm | 75% | 2.1 m/s | 6.2 |
| 2008 | 22.9°C | 20.8°C | 18.7°C | 27.2°C | 16.4°C | 0 mm | 77% | 2.3 m/s | 5.9 |
| 2007 | 22.1°C | 20.0°C | 17.8°C | 29.8°C | 15.7°C | 16 mm | 74% | 2.5 m/s | 6.1 |
| 2006 | 22.6°C | 20.3°C | 18.1°C | 26.9°C | 16.2°C | 0 mm | 73% | 2.3 m/s | 6.1 |
| 2005 | 22.1°C | 19.8°C | 17.5°C | 30.9°C | 14.8°C | 5 mm | 73% | 2.1 m/s | 6.1 |
| 2004 | 24.2°C | 21.9°C | 19.6°C | 31.6°C | 16.5°C | 0 mm | 72% | 2.2 m/s | 6.2 |
| 2003 | 21.9°C | 19.9°C | 17.9°C | 25.4°C | 16.3°C | 0 mm | 81% | 2.1 m/s | 5.8 |
| 2002 | 22.7°C | 20.4°C | 18.1°C | 27.5°C | 16.3°C | 2 mm | 74% | 2.3 m/s | 5.6 |
| 2001 | 21.9°C | 19.8°C | 17.6°C | 27.0°C | 15.8°C | 0 mm | 77% | 2.2 m/s | 5.9 |
| 2000 | 23.3°C | 21.0°C | 18.7°C | 29.1°C | 16.9°C | 6 mm | 73% | 2.3 m/s | 5.7 |
| 1999 ❄️ | 20.9°C | 18.8°C | 16.8°C | 31.9°C | 14.5°C | 0 mm | 77% | 2.4 m/s | 5.7 |
| 1998 | 22.4°C | 20.7°C | 19.1°C | 29.1°C | 17.1°C | 8 mm | 77% | 2.5 m/s | 5.4 |
| 1997 | 25.4°C | 23.2°C | 20.9°C | 28.2°C | 18.8°C | 12 mm | 74% | 2.2 m/s | 5.8 |
| 1996 | 22.8°C | 20.6°C | 18.5°C | 25.4°C | 16.9°C | 0 mm | 76% | 2.5 m/s | 5.8 |
| 1995 | 23.3°C | 21.1°C | 19.0°C | 26.3°C | 17.1°C | 0 mm | 73% | 2.2 m/s | 6 |
| 1994 | 23.1°C | 20.9°C | 18.8°C | 25.8°C | 16.7°C | 0 mm | 73% | 2.5 m/s | 5.7 |
| 1993 | 22.6°C | 20.2°C | 17.9°C | 27.7°C | 15.7°C | 0 mm | 72% | 2.3 m/s | 5.6 |
| 1992 | 24.0°C | 21.7°C | 19.3°C | 27.5°C | 17.1°C | 0 mm | 72% | 2.3 m/s | 6 |
| 1991 | 22.1°C | 20.0°C | 17.9°C | 26.0°C | 15.7°C | 3 mm | 77% | 2.1 m/s | 5.5 |
| 1990 | 24.2°C | 21.8°C | 19.5°C | 27.4°C | 17.7°C | 0 mm | 71% | 2.2 m/s | 6 |
| 1989 | 23.4°C | 20.8°C | 18.2°C | 28.2°C | 16.2°C | 10 mm | 69% | 2.3 m/s | 5.9 |
| 1988 | 23.5°C | 20.9°C | 18.3°C | 35.8°C | 15.9°C | 1 mm | 70% | 2.3 m/s | 5.3 |
| 1987 | 23.5°C | 21.1°C | 18.6°C | 29.2°C | 16.5°C | 2 mm | 74% | 2.2 m/s | 5.5 |
| 1986 | 21.4°C | 19.1°C | 16.8°C | 24.4°C | 15.1°C | 41 mm | 73% | 2.8 m/s | 5.6 |
| 1985 | 22.9°C | 20.6°C | 18.4°C | 25.9°C | 17.0°C | 4 mm | 69% | 2.5 m/s | 5.5 |
| 1984 🔥 | 27.1°C | 24.5°C | 22.0°C | 31.5°C | 19.4°C | 4 mm | 68% | 2.4 m/s | 5.3 |
| 1983 🌧️ | 25.2°C | 22.9°C | 20.6°C | 28.8°C | 18.2°C | 46 mm | 71% | 2.4 m/s | — |
| 1982 | 23.5°C | 21.2°C | 18.9°C | 29.6°C | 15.1°C | 20 mm | 69% | 2.5 m/s | — |
| 1981 | 23.5°C | 20.9°C | 18.3°C | 27.4°C | 16.4°C | 5 mm | 69% | 2.3 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 23.3°C with lows near 18.9°C (mean 21.1°C), based on 45 years of NASA POWER data.
September averages 6 mm of rainfall in Santa Ana, one of the drier months. The wettest on record was 46 mm in 1983.
The hottest September reached 35.8°C in 1988. The coldest dipped to 14.5°C in 1999.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have fallen by about 0.7°C. Daytime highs moved from 24.4°C to 23.2°C and overnight lows from 19.6°C to 19.4°C over the same span.
September is one of the warmer months of the year in Santa Ana and one of the drier months, so plan for around 23.3°C daytime highs and 18.9°C at night.
Not quite — September is the 11th coolest month in Santa Ana, averaging 21.1°C.
For September in Santa Ana, pack light layers you can adjust through the day, with typical highs of 23.3°C and lows of 18.9°C.
Relative humidity in September averages 74% — moderately humid.
Average wind speed in September is 2.3 m/s. The windiest September on record averaged 2.8 m/s (1986).
The wettest September on record was 1983 with 46 mm. On average, September sees 6 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 Santa Ana 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.
