Although the Algarve has Atlantic coastline, it experiences a Mediterranean climate with hot, dry summers, and mild winters.
From mid-May to mid-September the Algarve has almost constant sunshine with daily maximum temperatures peaking at around 27-32 degrees Celsius.
Spring and Autumn are mainly sunny with the odd rainy day with maximum temperatures in the low to mid 20s Celsius. In Winter there will be rainy days, but there are also plenty of mild sunny days with temperatures peaking at around 15-17 degrees Celsius.
Winter can be a fantastic time to explore the Algarve. There are periods of rain, but these generally only last a couple of days, and for the majority of the time the sun shines and temperatures are pleasantly mild. It is not uncommon to see tourist visitors in shorts and t-shirts during the winter months, whereas the locals will be wearing coats and scarves!
Night times in winter can be chilly however, typically dropping to around 5-10 degrees Celsius minimum. Although there is no frost on the Algarve coast, if you travel inland a few kilometres there can be a light frost in the early morning.
TIP: If you are travelling to the Algarve in winter, be sure to check if your accommodation has heating at night, as the houses are designed to keep the heat out.