Portugalete, Spain's climate is characterized by mild winters and warm summers. Winters are cool, with temperatures often below freezing in January and February, but can occasionally rise into the mid-20s Celsius. Spring brings rapid warming, with March and April averaging around 12°C and May reaching highs of over 30°C. Summer months from June to September are hot, with temperatures frequently exceeding 35°C, while autumn sees a gradual cooling back towards winter temperatures.