Chiayi City weather in September
In September, Chiayi City has daytime highs averaging 29 °C, nights around 23 °C, with 23 wet days. Figures are 1991–2020 climate normals.
- 28.7°C Average high
- 22.6°C Average low
- 23days Wet days
- 415mm Rainfall
- 12h Daylight
Daily temperatures through September
How September develops
Averages for the first, middle and last part of the month, from daily 1991–2020 normals. Chance of rain is the share of years in which that calendar day recorded more than 1 mm.
| Days | Avg high | Avg low | Chance of rain |
|---|---|---|---|
| 1–10 September | 28.9 °C | 23.0 °C | 85 % |
| 11–20 September | 28.8 °C | 22.6 °C | 77 % |
| 21–30 September | 28.4 °C | 22.2 °C | 71 % |
- Rain is most likely over days 1–10 of September (85 % of days) and least likely over days 21–30 (71 %).
What to expect
| Measure | Typical September | Share of the month |
|---|---|---|
| Days above 25 °C | 29 of 30 | 98 % |
| Days above 30 °C | 4.0 of 30 | 13 % |
| Days below 0 °C | 0 of 30 | 0 % |
| Days with more than 1 mm rain | 23 of 30 | 77 % |
Conditions in September
| Measure | Average |
|---|---|
| Mean temperature | 26 °C |
| Record high (1991–2020) | 34 °C |
| Record low (1991–2020) | 15 °C |
| Relative humidity | 85 % |
| Wind speed | 10 km/h |
| Cloud cover | 68 % |
September compared with the months around it
| Month | Avg high | Rainfall | Cloud |
|---|---|---|---|
| July | 29.7 °C | 535 mm | 77 % |
| August | 29.2 °C | 652 mm | 77 % |
| September | 28.7 °C | 415 mm | 68 % |
| October | 27.4 °C | 192 mm | 56 % |
| November | 25.4 °C | 76 mm | 51 % |
See all twelve months for Chiayi City
- September is the 4th warmest month here.
- It is the 10th driest month of the year.
- It ranks 8th for least cloud cover.
- Days last about 12 hours from sunrise to sunset.
- It rains on 23 of 30 days — 77 % of the month.
- Nights are about 6.1 °C cooler than the middle of the day.
- The hottest September day on record since 1991 reached 34 °C, 5.4 °C above the usual daytime high.
QuestionsSeptember in Chiayi City, answered
How warm is Chiayi City in September?
Daily highs average 29 °C and nights fall to about 23 °C, a spread of 6.1 °C between afternoon and dawn. That makes September the 4th warmest month of the year here.
Does it rain much in Chiayi City in September?
September averages 415 mm of rain, spread over about 23 of the 30 days — 77 % of the month. Cloud cover averages 68 % of the sky.
How long are the days in September?
Chiayi City averages 12 hours between sunrise and sunset in September. Day length is computed from latitude and date, so it is exact rather than modelled — but it says nothing about how much of that time is sunny.
Data sources and method
- ERA5 / ERA5-Land reanalysis — Copernicus Climate Change Service (C3S), ECMWF. Copernicus Licence
- Open-Meteo — Open-Meteo.com. CC BY 4.0
- NOAA OISST v2.1 — NOAA Physical Sciences Laboratory. Public domain
- GeoNames — GeoNames.org. CC BY 4.0
- Normal period
- 1991–2020
- Dataset version
- era5-1991-2020-scores1.1
- Last processed
Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: daylight hours, beach and comfort scores, monthly rankings, threshold day counts, chance of a wet day by date, ten-day averages within the month. Full formulas are on the methodology page.
Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.