Map from Google - Lisbon

In Lisbon, capital of Portugal, the climate is Mediterranean, mild and rainy in winter, warm and sunny in summer. The location, in the far west of Europe and overlooking the ocean, makes the climate particularly mild, compared with other European countries. Here are the average temperatures.
Average temperatures - Lisbon
Min (°F)464852545763646664595450
Max (°F)596166687279828281736459

Rainfall amounts to 28 inches per year, and follows a Mediterranean pattern, being abundant in autumn and winter, moderate and less frequent in spring, and very scarce in summer. In some years, autumn and winter can be particularly rainy.
Here is the average precipitation.
Average precipitation - Lisbon
Prec. (in)4.34.332.

Winter, from December to February, is mild: the average January temperature is 52.5 °F. Daytime temperatures are generally mild, around 59/61 °F. The westerly winds prevail, bringing quite frequent rains, sometimes abundant, and windy conditions. There are also periods of good weather, since the Azores anticyclone can move over Portugal even in winter. Very cold days are rare: sometimes there can be days with lows about 36/37 °F, and highs about 46.5/50 °F, while the temperature never drops below freezing: the coldest record is 32 °F. Snow is a very rare phenomenon: someone still remembers the snowfall of 1954, or the more recent (and less intense) one of 2006.

Spring, from March to May, is mild, with some periods of bad weather, which become rare from the second half of April, and nice weather becoming more and more frequent.

Summer, from June to mid-September, is warm and sunny: the average temperature is 74.5 °F in August, so it is not too high, and besides the breeze blows from the ocean, tempering the heat. The clearness of the air shows that we are not on the Mediterranean coasts, where summer tends to be more hot and muggy. Typically the temperatures are pleasant, so that highs don't reach 85 °F, and lows slightly drop below 68 °F, although there may be also hot periods, due to African air masses: in these cases the temperature can reach 97/100 °F, and sometimes even 105 °F.

Autumn, from mid-September to November, is initially warm and sunny, but gradually becomes milder, while waves of bad weather become more frequent. November is a rainy month.

The amount of sunshine in Lisbon is very good in summer, when the weather is almost always sunny; it's also good in spring and early autumn, while in late autumn and winter there are cloudy periods, shorter or longer, alternating with sunny periods.


For swimming, the sea in Lisbon is definitely cool, or even a little cold, even in summer: the water temperature goes to 64 °F in June, to 66 °F in July, to 68 °F in August and September.
Here are the average sea temperatures.
Sea temperature - Lisbon
Sea (°F)595959616364666868666463

When to go

The best months to visit Lisbon are May, June and September, being generally mild or pleasantly warm, and sunny. Even in July and August the temperature is generally acceptable, but there is a higher risk of hot days.