San Sebastián Temperature by Month

The average annual maximum temperature in San Sebastián, Basque Country, Spain is 17°C (63°F), with daytime highs ranging from 12°C (54°F) in January to 24°C (75°F) in August. This page covers monthly averages, day-night differences, and how San Sebastián compares to cities worldwide.

The climate in San Sebastián is known for significant temperature differences throughout the year. At night, this contrast is just as clear, with lows ranging from 18°C (64°F) in August to 7°C (45°F) in January.

The chart below illustrates the average maximum day and minimum night temperatures in San Sebastián by month:

Temperatures tend to bottom out between 4 AM and 6 AM, then climb to their daily peak around 3 PM. August, the warmest month, sees 198 hours of sunshine.

The chart below shows the average temperature throughout the year:

San Sebastián's average annual maximum temperature is 17°C (63°F). To put that in context, here's how it compares to a few well-known destinations:

Seville, Spain averages 23°C (73°F) a year, one of the warmer cities in Western Europe, with long hot summers.

Toronto, Canada averages 13°C (55°F) annually, with cold snowy winters balanced by genuinely warm summers.

Boston, USA averages 16°C (61°F) annually, with four distinct seasons and cold winters that rival northern Europe.

Adelaide, Australia averages 21°C (70°F) a year, with warm summers, mild winters, and relatively low rainfall year-round.

Temperature alone doesn't tell the whole story, humidity plays a big role in how warm or cold it actually feels. High humidity in summer makes the heat feel more intense, particularly once temperatures climb above 25°C. In winter, the same humidity can make cold air feel sharper than the thermometer suggests.

In the cooler months, when temperatures drop below 10°C, high humidity makes the cold feel more cutting than it would in dry conditions.

In San Sebastián, January is the coolest month, with average highs of 12°C (54°F) and humidity around 75%, considered high. In August, the warmest month, temperatures average 24°C (75°F) with 75% humidity, conditions that feel high. For a full picture, see our humidity page.

Climate temperature data is typically calculated as a 30-year average. This smooths out year-to-year variability and gives a more reliable picture of what a place is actually like, rather than what happened in any single unusual year.

The readings come from a range of sources, land-based weather stations, ocean buoys, ships, and satellites. That data is collected by weather services around the world, then pooled, quality-checked, and averaged to produce the climate records you see here.

Global average temperatures have risen by around 1.2°C since the pre-industrial era, and the effects are visible across many regions. Winters are milder on average, with fewer frost days and less snow in many parts of the world. Heatwaves are more frequent and more intense, and Europe's summers of 2018, 2019, and 2020 all set records.

Summers are also getting drier in some areas, while winter rainfall has increased in others. This contributies to higher river levels and more flooding. In many countries, spring arrives earlier and autumn lasts longer. It has knock-on effects for wildlife, agriculture, and local ecosystems.

For more on San Sebastián's weather, including monthly rainfall, sunshine hours, and humidity, visit our San Sebastián climate page.