Portugal and northern Spain are often lumped into the same “best time to visit” advice as southern Europe, which usually amounts to “avoid August” and little else. For a route that actually crosses both—say, Lisbon through Porto, Santiago de Compostela, and San Sebastián—the timing question is more specific because the two ends of the trip follow different weather patterns, beyond the general best time to visit Europe guidance.
Lisbon and Porto: shoulder season over summer
Both cities are walkable-first destinations—see the Lisbon travel guide for basing details—think Alfama’s hills and Porto’s riverside steps—and July and August heat can make that kind of walking genuinely unpleasant by early afternoon. May, June, September, and October generally keep daytime temperatures in a range where a full day on foot does not require retreating indoors from 1 to 4 p.m. October also thins out the cruise-ship crowds that fill Porto’s riverside in peak summer.
Santiago de Compostela: less weather-sensitive
Galicia’s climate is wetter and cooler year-round than Portugal’s coast, which makes it comparatively weather-insensitive as a stop. It is a reasonable addition in most months, including those that would be too cool or wet for a coastal Portugal-only trip.
San Sebastián: the one city where summer has a real case
This is the exception. San Sebastián’s appeal leans heavily on Playa de la Concha and the beach culture around it, and that’s genuinely better in July/August than in October. The trade-off is pintxos-bar crowding and higher lodging cost at the same time. Early October is the compromise: beach weather usually still holds, and both crowding and price drop from peak.
The route-level answer
For a route that treats all four cities as roughly equal stops, early to mid-October comes out ahead of peak summer overall. You give San Sebastián a little less certainty on beach weather in exchange for a meaningfully better experience in Lisbon, Porto, and Santiago de Compostela. If San Sebastián’s beach is the priority, shift the whole route two to three weeks earlier and accept the trade-off elsewhere.
Want to see how a shift in dates changes the cost, not just the weather odds? Describe your dates to the planner and compare.
