September is one of the warmer months of the year in Chula Vista, with average highs near 29°C and lows around 17.4°C (mean 23.2°C). It is one of the drier months, averaging 9 mm of rainfall and 58% relative humidity across the period.
September is one of the warmer months of the year in Chula Vista. Across 45 years of records, the warmest September in Chula Vista was 1984 — when the month averaged 25.9°C — while the coldest was 1986 at 19.4°C. Typical September days reach 29°C with nights near 17.4°C. The long-term September temperature trend is broadly flat.
September is one of the drier months in Chula Vista, averaging 9 mm of rainfall. The wettest September on record was 2025 with 93 mm, while the driest was 2020 at 0 mm.
Relative humidity in Chula Vista during September averages 58%. The most humid September was 2023 at 72%, and the least humid was 2020 at 48%.
September receives about 5.3 kWh/m²/day of solar energy in Chula Vista. The sunniest September was 2014 at 6 kWh/m²/day, and the cloudiest was 2011 at 4.4.
Average wind speed in Chula Vista during September is 2 m/s. The windiest Septembers were 2007, 2017 and 2023, among others at 2.3 m/s, while the calmest was 1991 at 1.6 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 22.8°C | 23.1°C | 23.1°C | 23.4°C | 23.5°C | +0.7°C |
| Avg High | 28.7°C | 28.8°C | 29.1°C | 29.2°C | 29.1°C | +0.4°C |
| Avg Low | 17.0°C | 17.3°C | 17.2°C | 17.6°C | 17.8°C | +0.8°C |
| Avg Rain | 11 mm | 6 mm | 4 mm | 8 mm | 21 mm | +10 mm |
September temperatures in Chula Vista have fallen by about 0.4°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 10.8°C (1986) to a record high of 39.1°C (2020).
Rainfall in September is one of the drier months, averaging 9 mm, with a wettest year of 93 mm.
One of the best times to visit Chula Vista
September is one of the best times to visit Chula Vista. Expect days averaging 29°C and nights around 17.4°C (mean 23.2°C) — warmer than Chula Vista's yearly average — with low rainfall (9 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 🌧️ | 28.0°C | 23.0°C | 18.0°C | 34.0°C | 15.5°C | 93 mm | 68% | 2 m/s | 5.2 |
| 2024 | 29.3°C | 23.5°C | 17.7°C | 38.7°C | 13.1°C | 1 mm | 58% | 2 m/s | 5.3 |
| 2023 | 25.9°C | 21.0°C | 16.1°C | 32.7°C | 12.7°C | 4 mm | 72% | 2.3 m/s | 5 |
| 2022 | 29.8°C | 24.6°C | 19.4°C | 36.8°C | 13.8°C | 24 mm | 63% | 1.9 m/s | 5.5 |
| 2021 | 29.4°C | 23.2°C | 16.9°C | 35.1°C | 12.3°C | 3 mm | 57% | 1.9 m/s | 5.5 |
| 2020 | 32.0°C | 25.4°C | 18.8°C | 39.1°C | 14.4°C | 0 mm | 48% | 1.7 m/s | 5.6 |
| 2019 | 28.4°C | 23.0°C | 17.6°C | 34.3°C | 11.6°C | 10 mm | 60% | 2.1 m/s | 5.7 |
| 2018 | 29.1°C | 22.7°C | 16.2°C | 33.6°C | 14.0°C | 1 mm | 57% | 1.9 m/s | 5.1 |
| 2017 | 27.7°C | 22.5°C | 17.3°C | 38.2°C | 12.3°C | 2 mm | 63% | 2.3 m/s | 5.5 |
| 2016 | 27.7°C | 22.1°C | 16.5°C | 32.6°C | 12.8°C | 22 mm | 60% | 2 m/s | 5.2 |
| 2015 | 30.0°C | 24.7°C | 19.4°C | 36.2°C | 14.0°C | 21 mm | 64% | 2 m/s | 5.7 |
| 2014 | 30.6°C | 24.8°C | 19.1°C | 36.8°C | 14.3°C | 2 mm | 61% | 2 m/s | 6 |
| 2013 | 28.8°C | 23.2°C | 17.5°C | 34.1°C | 11.4°C | 11 mm | 58% | 1.9 m/s | 5.6 |
| 2012 | 31.6°C | 25.5°C | 19.5°C | 35.4°C | 14.1°C | 4 mm | 50% | 1.8 m/s | 5.6 |
| 2011 | 29.0°C | 22.7°C | 16.4°C | 36.5°C | 12.8°C | 5 mm | 56% | 1.8 m/s | 4.4 |
| 2010 | 28.8°C | 22.6°C | 16.3°C | 38.3°C | 12.3°C | 5 mm | 54% | 1.8 m/s | 5 |
| 2009 | 30.7°C | 24.6°C | 18.4°C | 35.9°C | 13.0°C | 1 mm | 50% | 1.8 m/s | 5.5 |
| 2008 | 30.0°C | 23.9°C | 17.9°C | 35.5°C | 13.6°C | 3 mm | 57% | 1.9 m/s | 5.1 |
| 2007 | 27.0°C | 21.5°C | 16.0°C | 36.3°C | 11.9°C | 3 mm | 61% | 2.3 m/s | 5.8 |
| 2006 | 29.2°C | 23.2°C | 17.2°C | 35.0°C | 12.5°C | 2 mm | 55% | 1.8 m/s | 5.6 |
| 2005 | 27.4°C | 21.6°C | 15.7°C | 34.8°C | 11.7°C | 2 mm | 55% | 1.9 m/s | 5.7 |
| 2004 | 28.9°C | 23.0°C | 17.2°C | 35.1°C | 13.0°C | 2 mm | 56% | 2.1 m/s | 5.6 |
| 2003 | 30.4°C | 24.0°C | 17.6°C | 34.7°C | 13.9°C | 4 mm | 60% | 1.8 m/s | 4.8 |
| 2002 | 29.3°C | 23.6°C | 17.9°C | 37.4°C | 13.7°C | 12 mm | 54% | 1.8 m/s | 5 |
| 2001 | 29.1°C | 22.8°C | 16.6°C | 34.4°C | 12.8°C | 4 mm | 58% | 1.8 m/s | 4.8 |
| 2000 | 28.7°C | 22.8°C | 17.0°C | 35.5°C | 13.2°C | 4 mm | 58% | 2.1 m/s | 5.3 |
| 1999 | 27.5°C | 21.4°C | 15.2°C | 34.9°C | 11.8°C | 7 mm | 62% | 2.1 m/s | 4.6 |
| 1998 | 26.7°C | 21.6°C | 16.6°C | 36.0°C | 12.6°C | 4 mm | 66% | 2.2 m/s | 5.3 |
| 1997 | 30.3°C | 24.8°C | 19.4°C | 34.6°C | 14.5°C | 34 mm | 61% | 1.9 m/s | 5.5 |
| 1996 | 28.0°C | 22.3°C | 16.7°C | 32.7°C | 14.0°C | 1 mm | 65% | 2 m/s | 5.1 |
| 1995 | 30.0°C | 24.2°C | 18.5°C | 34.5°C | 13.4°C | 2 mm | 54% | 1.9 m/s | 5.5 |
| 1994 | 28.3°C | 22.6°C | 17.0°C | 33.2°C | 12.4°C | 0 mm | 58% | 1.9 m/s | 5.6 |
| 1993 | 29.1°C | 23.1°C | 17.0°C | 36.4°C | 12.0°C | 1 mm | 53% | 1.9 m/s | 5 |
| 1992 | 30.3°C | 24.1°C | 18.0°C | 34.3°C | 14.7°C | 0 mm | 53% | 1.7 m/s | 5.6 |
| 1991 | 28.5°C | 22.8°C | 17.2°C | 33.5°C | 11.9°C | 6 mm | 62% | 1.6 m/s | 4.6 |
| 1990 | 29.4°C | 23.7°C | 17.9°C | 36.3°C | 14.3°C | 5 mm | 57% | 2 m/s | 5.4 |
| 1989 | 29.3°C | 23.2°C | 17.1°C | 34.4°C | 11.6°C | 6 mm | 51% | 1.9 m/s | 5.6 |
| 1988 | 28.8°C | 22.6°C | 16.3°C | 37.2°C | 11.9°C | 1 mm | 57% | 2.1 m/s | 4.7 |
| 1987 | 29.0°C | 22.8°C | 16.7°C | 36.6°C | 13.4°C | 15 mm | 59% | 1.8 m/s | 4.7 |
| 1986 ❄️ | 25.0°C | 19.4°C | 13.9°C | 33.3°C | 10.8°C | 23 mm | 63% | 2.3 m/s | 4.9 |
| 1985 | 26.2°C | 20.9°C | 15.7°C | 31.9°C | 11.9°C | 10 mm | 60% | 2.3 m/s | 5.4 |
| 1984 🔥 | 31.9°C | 25.9°C | 20.0°C | 39.0°C | 14.6°C | 5 mm | 56% | 2.1 m/s | 5.4 |
| 1983 | 30.2°C | 24.6°C | 19.1°C | 36.9°C | 14.5°C | 14 mm | 59% | 2 m/s | — |
| 1982 | 28.0°C | 22.6°C | 17.2°C | 36.8°C | 11.8°C | 17 mm | 61% | 2.2 m/s | — |
| 1981 | 29.8°C | 23.5°C | 17.2°C | 34.9°C | 12.7°C | 5 mm | 52% | 1.9 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 29°C with lows near 17.4°C (mean 23.2°C), based on 45 years of NASA POWER data.
September averages 9 mm of rainfall in Chula Vista, one of the drier months. The wettest on record was 93 mm in 2025.
The hottest September reached 39.1°C in 2020. The coldest dipped to 10.8°C in 1986.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have fallen by about 0.4°C. Daytime highs moved from 29.2°C to 28.5°C and overnight lows from 17.8°C to 17.6°C over the same span.
September is one of the warmer months of the year in Chula Vista and one of the drier months, so plan for around 29°C daytime highs and 17.4°C at night.
Not quite — September is the 11th coolest month in Chula Vista, averaging 23.2°C.
For September in Chula Vista, pack light layers you can adjust through the day, with typical highs of 29°C and lows of 17.4°C.
Relative humidity in September averages 58% — moderately humid.
Average wind speed in September is 2 m/s. The windiest September on record averaged 2.3 m/s (1985).
The wettest September on record was 2025 with 93 mm. On average, September sees 9 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 Chula Vista 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.
