If you plan to visit San Sebastian in September, the weather is typically alright, with an average high temperature of +73°F during the day and approximately 6 sunny days. Expect some rainy, though, as there are typically 15 rainy days in the month and around 109 mm of precipitation. The weather is changeable so you may have to pack for every eventuality. Search flightsin one click on Avionero.
Average weather
☀️
+73°F
Avg. max. temperature
+45°F
Min.
+99°F
Max.
109 mm
Total precipitation
78%
Avg. humidity
2 m/s
Avg. wind
6 ☀️
Sunny Days
7 ⛅️
Cloudy
15 🌦
Rainy
Our opinion: San Sebastian has OK weather in September.
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Average temperature in San Sebastian in September
Here are the expected maximum, average and minimum temperatures in San Sebastian for September based on the historical data.
Last Year
Historical Data
Going from a maximum of +91°F during the day to a minimum of +55°F during the night, the temperature in September averages around +79°F.
The average maximum temperature goes up 10% by the end of the month, compared with the beginning of the month, from +77°F to +81°F.
Is San Sebastian warm or cold in September?
San Sebastian is typically warm in September.
Maximum temperatures go down compared to the previous month from +75°F to +73°F. The minimum temperature also goes down from +64°F to +61°F.
It’s generally warm, but pack a long-sleeve shirt for evenings.
September is one of the warmest months in San Sebastian, here is the comparison with other months:
Water temperature in San Sebastian in September
Water in San Sebastian in September is Fresh. It varies from +65°F to +73°F, with an average of +69°F.This is almost similar to the air temperature, which averages +73°F.
The water temperature in September is one of the warmest of the entire year:
The warmest water temperatures in San Sebastian are reached in August, when the average sea temperature rises to +70°F. The coldest water temperatures are in February, with an average of +54°F.
Can you swim in San Sebastian in September?
Water temperature (+69°F) in San Sebastian in September might be suited for short swims and acclimatized swimmers might find it refreshing.
🦭
Cold
Below +61°F
🏄♂️
Fresh
61°F - 70°F
🏊
Comfortable
70°F - 77°F
👙
Warm
77°F - 82°F
🔥
Very warm
+82°C and up
Think of bringing a full-body or shorty wetsuit (3mm-5mm thickness) to provide insulation and maintain body heat.
Climate in San Sebastian in September
San Sebastian weather looks like this, on average, in September and the surrounding months.
August
September
October
Avg. temperature
+75°F
+73°F
+68°F
Min. temperature
+54°F
+45°F
+36°F
Max. temperature
+102°F
+99°F
+88°F
Rainfall
102 mm
109 mm
144 mm
Wind
1 m/s
2 m/s
2 m/s
Avg. water temperature
+70°F
+69°F
+66°F
Humidity
80%
78%
77%
Air pressure
1017 HPa
1017 HPa
1016 HPa
Sunny days
5
6
6
Cloudy days
8
7
7
Rainy days
16
15
17
Snowy days
0
0
0
September weather is still as ok as in August.It’s getting colder in September. From +75°F in the day, the average maximum temperature lowers to +73°F.Prepare for more rain. Average rainfall goes from 102 mm to 109 mm.It feels drier, as humidity decreases from 80% to 78%.Winds are stronger in comparison to August, going up from 1 m/s to 2 m/s on average.The good news is there are likely to be more sunny days in September, from 5 to 6.
October brings much the same weather, it remains ok.
Wind speed in San Sebastian in September based on historical data.
Last Year
Historical Data
The average wind speed is 2 m/s getting up to 4 m/s which is a light breeze; barely moving the tree leaves.
The average wind speed in San Sebastian is gradually decreasing during September, going from 2 m/s to 1 m/s over the course of the month.
Rain
Amount of rainfall in mm during September in San Sebastian based on historical data.
Last Year
Historical Data
Typically, there is a 50% chance of rain on an average day in September, with total rainfall of approximately 189 mm. The maximum amount of rainfall per day is around 43 mm, which is moderate rain.September is a pretty wet month with over 15 rainy days, so don’t forget to pack an umbrella, raincoat, and a pair of wellies.
Here’s how September is compared with other months in the amount of precipitation, total mm:
San Sebastian wettest month is November, where a typical day has a 60% chance of precipitation and 191 mm of rainfall per day. July, on the other hand, is the driest month with a mere 52% chance of precipitation and 93 mm of rainfall per day.
How was the weather last September in San Sebastian?
This is the weather in San Sebastian in September 2024:
1 September
☀️
+77°F
2 September
🌧️
+67°F
3 September
☀️
+77°F
4 September
☀️
+88°F
5 September
☀️
+87°F
6 September
☀️
+86°F
7 September
☀️
+90°F
8 September
☀️
+83°F
9 September
☀️
+92°F
10 September
☀️
+80°F
11 September
🌧️
+79°F
12 September
🌧️
+72°F
13 September
🌧️
+73°F
14 September
☁️
+76°F
15 September
☀️
+80°F
16 September
☁️
+83°F
17 September
☀️
+83°F
18 September
☁️
+78°F
19 September
☀️
+75°F
20 September
☀️
+82°F
21 September
🌧️
+75°F
22 September
🌧️
+67°F
23 September
🌧️
+70°F
24 September
☀️
+85°F
25 September
☀️
+75°F
26 September
☀️
+73°F
27 September
☀️
+85°F
28 September
☀️
+85°F
29 September
☀️
+77°F
30 September
☀️
+80°F
In September 2024 San Sebastian had 20 sunny days, 3 cloudy days, and 7 rainy days. The average maximum temperature was +79°F, with an absolute maximum of +91°F and a minimum of +66°F. The average humidity was 80%, with a maximum of 100% and a minimum of 54%. The average wind speed was 2 m/s, with a maximum of 7 m/s and a minimum of 0 m/s.
Are you planning a trip in September?
Climate Change Over the Years
This is how San Sebastian climate has changed over the last 43 years.
The climate in San Sebastian in September has not changed that much over the last 43 years.
The average temperature was the lowest in 1984 (+61°F) and the highest in 2022 (+68°F). The driest year was 1989 with only 973 mm of rainfall, and the wettest year was 2019 with 4351 mm.
FAQ
Frequently asked questions about the weather in San Sebastian in September:
Is September a good time to visit San Sebastian?
It’s always a good time to visit San Sebastian, but the weather is changeable in September, so plan a mix of indoor and outdoor activities and exploring, and pack for every eventuality.
Can you sunbathe in San Sebastian in September?
September is warm in San Sebastian. You may enjoy some beach or pool time in the day, but pack something a tad warmer for the evening.
Can you swim in San Sebastian in September?
In general, you can swim in San Sebastian in September, if you want to, at an average water temperature of +69°F. But it will feel quite cool, and some precautions are necessary to ensure your comfort and safety.
Is San Sebastian rainy in September?
San Sebastian is often rainy in September. You may get a bit damp when outside, so pack an umbrella, and maybe even a raincoat.
Is it sunny in San Sebastian in September?
Usually, it’s not very sunny in San Sebastian in September, often it’s pretty cloudy. Pack for any eventuality; layering can help reduce the number of bulky items needed.
For this page, we’ve looked at the typical weather in San Sebastian, based on historical hourly weather data from January 1, 1979, to December 31, 2023.
For past dates, we show actual recorded data at the location at that time. Forecasts are based on recorded weather during that day of the year, averaged over the total years for which we have records (unless stated otherwise). The daily temperature is the highest recorded temperature in the shadow during that day.
