Porto in September
In September, Porto has 59.5 mm (2.34 in) of rain, a daily high of 25.6 °C (78.1 °F) and a daily low of 15.9 °C (60.6 °F), as 1991-2020 model estimates; figures in brackets are converted. The daily high is a model estimate, adjusted against station records.
Last updated : first sourced version.
Best time to visit Porto: September meets our rule. Expect 5.7 rain days (model estimate) and days that shorten by 1 h 18 min.
What September is like in Porto
- In September, the Porto Book Fair sets up about a hundred and thirty stalls in the Palácio de Cristal gardens. Old book dealers come as well as publishers. Source: Câmara Municipal do Porto (Porto city council), checked .
- In early September, Port Wine Day is marked in Porto. One year it closed with a regatta of rabelo boats on the Douro. Source: Câmara Municipal do Porto (Porto city council), checked .
- In late September, for European Heritage Days, the Museu do Porto runs two days of free workshops and talks. Source: Câmara Municipal do Porto (Porto city council), checked .
Key figures
Weather in September, 1991-2020 model estimates
- Daily high
- 25.6 °C (78.1 °F)
- Daily low
- 15.9 °C (60.6 °F)
- Rain
- 59.5 mm (2.34 in) in the month
- Sunshine
- no data
Model estimate 1991-2020, not a weather station: ERA5-Land model estimates (Copernicus), computed by City by Month for the grid cell nearest the city. Daily high and Days with rain: model estimate, adjusted against station records. Licence: CC BY 4.0. Checked . How we make and test model estimates
Model estimate for the ERA5-Land grid cell at 41.1° N, 8.6° W, 6 km from the city centre point.
How we define and convert these figures
Notes. Sunshine: Not in our ERA5-Land estimates.
Daylight on 15 September 2026
- Sunrise
- 07:15 local time
- Sunset
- 19:44 local time
- Day length
- 12 h 29 min
Day length 1-30 September: 13 h 06 min to 11 h 48 min, -1 h 18 min.
Source: NOAA Solar Calculator equations, checked .
Month by month
Each month: daily high in °C, then rain in mm, 1991-2020 model estimates.
ERA5-Land model estimates 1991-2020, as above, checked .
This month against the year
| Measure | September | Rank |
|---|---|---|
| Daily high | 25.6 °C | 3rd warmest |
| Daily low | 15.9 °C | 3rd warmest |
| Rain | 59.5 mm | 4th driest |
| Sunshine | no data | no data |
| Day length | 12 h 29 min | 6th longest |
Equal values share a rank. How we rank months
Porto in September, on average: 5.7 rain days (1 mm or more). Model estimate, adjusted against station records.
ERA5-Land model estimates 1991-2020, as above, checked .
Day length: NOAA solar equations, checked .
Public holidays this month
September 2026: none.
Typed from the official list and re-checked, .
September 2027: no data. No official page gives the 2027 Easter and Corpus Christi dates yet.
Source: Official public holiday list (dgaj.justica.gov.pt), checked ; holidays Python library, checked . Library: holidays 0.105.
Same month in 8 model-estimate cities
Porto is warmer than 3 of our 8 model-estimate cities in September by mean daily high. How we rank cities
Closest high and low in September: Istanbul (1.4 °C apart, equal), Lisbon (1.4, equal), Sydney (4.3).
| City | Gap from Porto, °C | High, °C | Low, °C | Rain, mm | Sunshine, hours |
|---|---|---|---|---|---|
| Porto (this page) | — | 25.6 | 15.9 | 59.5 | no data |
| Istanbul (closest) | 1.4 | 25.2 | 18.2 | 49.0 | no data |
| Lisbon (closest) | 1.4 | 26.1 | 18.2 | 31.2 | no data |
| Sydney (closest) | 4.3 | 21.1 | 11.9 | 49.1 | no data |
| Mumbai | 6.6 | 29.8 | 24.9 | no data | no data |
| Bangkok | 7.9 | 32.1 | 25.2 | no data | no data |
| Melbourne | 8.1 | 17.4 | 7.9 | 67.4 | no data |
| Delhi | 8.2 | 33.7 | 24.2 | no data | no data |
Sources (1991-2020): ERA5-Land model estimates, checked . Each city's page names its grid cell. All sources in full on Methodology.
Sources
- Attribution: Copernicus Climate Change Service (2025): ERA5 Land hourly time-series data from 1950 to present. Copernicus Climate Change Service (C3S) Climate Data Store (CDS). DOI: 10.24381/ee82e357. Accessed on the check date shown. Generated using or contains modified Copernicus Climate Change Service information 2025. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains. Licence: CC BY 4.0. Checked .
- NOAA Solar Calculator equations, computed locally, NOAA Global Monitoring Laboratory (method); City by Month (computation). Attribution: Computed with the NOAA Solar Calculator method (no NOAA endorsement implied). Licence: Method, not data. Checked .
- holidays Python library, run locally. Attribution: holidays library, Vacanza team. Licence: MIT. Checked .
Official sources
Cite this page: City by Month. "Porto in September: weather, daylight, holidays". https://citybymonth.com/cities/portugal/porto/september/. Last updated 8 November 2026.