Porto Weather

Porto features the Mediterranean climate (Köppen climate classification Csb). As a result, its climate shares many characteristics with the coastal south: warm, dry summers and mild, rainy winters. Unlike the south, however, cool and rainy interludes can interrupt the dry season and the season's average length is usually shorter, with three dry months. Mean annual precipitation is high and Porto is one of the wettest cities of Europe. However, long periods with mild temperatures and sunny days are frequent even during the rainiest months.

Summers are typically sunny with average temperatures between 16 °C (61 °F) and 27 °C (81 °F) but can rise to as high as 40 °C (104 °F) during occasional heat waves. During such heat waves the humidity remains quite low but nearby forest fires can add haze and ash to the air making breathing somewhat uncomfortable, especially at night. Nearby beaches are often windy and usually cooler than the urban areas. In contrast, occasional summer rainy periods may last a few days and are characterised by showers and cool temperatures of around 20 °C (68 °F) in the afternoon. However, summer average temperatures are a few degrees cooler than those expected at more continentally Mediterranean influenced metropolises on the same parallels such as Barcelona and Rome.

Winter temperatures typically range between 5 °C (41 °F) during morning and 15 °C (59 °F) in the afternoon but rarely drop below 0 °C (32 °F) at night. The weather is often rainy for long stretches although prolonged sunny periods do occur.

source: wikipedia