Month guide · Castro Marim, Portugal
Castro Marim in September: weather and what to expect
In September, Castro Marim averages highs of 29°C and lows of 19°C, with about 3 rainy days and 22 mm of rain. Highs are 4°C cooler than in August and 5°C warmer than in October. Crowds in the Algarve are medium.
Is September a good time to visit?
Good for
No verdicts for Castro Marim in September yet. They only use climate values that are precise enough to judge with.
Not ideal for
Nothing stands out as a weaker fit.
Daily highs through September
Town-level · ERA5-Land 1991-2020Highs fall about 5°C over the month. A day above 35°C happens in roughly 1 September in 3; nights below 15°C in about 1 in 2.
September in detail
Town-level · ERA5-LandCrowds, holidays and daylight
Public holidays in September 2027
No national or regional public holidays.
Local (municipal) holidays are not included.
Warmer in September
Where is warm in September →| Place | High | Rain days | From Castro Marim |
|---|---|---|---|
| Mértola, Alentejo | 30°C | 4 | 51 km |
| Minas de São Domingos, Alentejo | 29°C | 4 | 51 km |
| Serpa, Alentejo | 29°C | 4 | 82 km |
| Cabeça Gorda, Alentejo | 29°C | 4 | 84 km |
| Salvada, Alentejo | 29°C | 4 | 85 km |
The nearest towns with a warmer September. Distances are in a straight line.
How September is changing
Town-level · ERA5-LandSeptember highs are 1.6°C warmer than in 1991-2000, and September rainfall is down about 30% (2016-2025 against 1991-2000). Days above 30°C in September went from 9.3 to 14 a year on average.
Questions about Castro Marim in September
How warm is Castro Marim in September?
Average highs are 29°C and lows 19°C. August averages 33°C and October 24°C.
Does it rain much in Castro Marim in September?
About 3 days have at least 1 mm of rain, with 22 mm in total over the month.
Is Castro Marim busy in September?
In September 2025, nights booked through online platforms in the Algarve were about 55% of the busiest month, which we count as medium. The figure is for the whole region and leaves out hotels.
How long are the days in Castro Marim in September?
About 12 h 29 min from sunrise to sunset in the middle of the month.
Sources
Climate: ERA5-Land, Copernicus Climate Change Service (C3S) Climate Data Store, contains modified Copernicus information (CC BY 4.0). Crowds: Eurostat, nights spent in short-stay accommodation booked through online platforms (tour_ce_omn12) (CC BY 4.0). Place names and populations: GeoNames (CC BY 4.0). Climate averages cover 1991-2020. Daylight: calculated from the town's coordinates. Full methodology