Clima en Costa de Caparica en mayo

May is the one I keep coming back for. Mid-20s by day, cool enough at night for a jacket on the Alfama miradouros, and the jacarandas go purple around Praça do Príncipe Real toward the end of the month. Tourist crowds are already real but the Atlantic hasn't warmed up yet — swimming is for August.

Lisbon-area forum threads describe January as running around 15C in the day and 7-10C at night on average, with real variation depending on the day - a sunny stretch can reach the high teens C, while a grey, rainy one might barely clear 10C with nights near 5C. Posters recommended warm layers and sturdy, non-slip footwear, since wet cobblestones are a genuine hazard on rainy days around the wider Lisbon coast. Costa da Caparica, just across the river, follows this same general Atlantic winter pattern rather than anything milder or wetter.

Forum posters describe a steady, pleasant Atlantic breeze here that keeps July temperatures from feeling too intense, though it also means the ocean itself stays genuinely cold - posters describe water temperatures under 20C even at the height of summer, more suited to surfing (with a wetsuit) than casual swimming. A light jacket for evenings is standard advice despite the warm days. Posters flag a practical logistics point for anyone coming from Lisbon: bus traffic to and from Costa da Caparica gets genuinely heavy in summer, so a trip that normally takes around 30 minutes can run considerably longer during peak July-August crowds.