, with mild, rainy winters and warm, sunny summers. The city is not located right on the Atlantic coast, but at the mouth of the Tagus River, which widens into a bay (the Sea of Straw). However, due to its position in southwestern Europe and to the influence of the ocean, the climate is particularly mild.
The weather is influenced by Atlantic disturbances, which pass mainly from October to April, and by the Azores Anticyclone, which can settle all year round, but especially in summer.
of the coldest month (January) is of 11.8 °C (53.2 °F), that of the warmest month (August) is of 23.6 °C (74.6 °F).
amounts to 810 millimeters (32 inches) per year, and follows the Mediterranean pattern, in fact, it is abundant in autumn and winter, moderate and less frequent in spring, and definitely scarce in summer. During some years, autumn and winter can be particularly rainy.
, from December to February, is mild. Daytime temperatures are generally mild, around 15/16 °C (59/61 °F). The westerly winds prevail, bringing quite frequent rains, sometimes abundant, and windy conditions. There are also periods of good weather, since, as mentioned, the Azores Anticyclone can move over Portugal also in winter. During these periods, fog can form at night and in the early morning.
Very cold days are rare: sometimes, there can be short periods with temperatures about 2/3 °C (36/37 °F) at night and about 8/10 °C (46/50 °F) during the day.
Snow in Lisbon is a very rare phenomenon: some still remember the snowfall of February 1954, while a more recent snowfall, though lighter, occurred in January 2006. The temperature almost never drops below freezing. The coldest record is -1 °C (30 °F), recorded in February 1954 (after the snowfall) and in February 1956.
, from March to May, is mild, with some periods of bad weather, which become rare by the second half of April, while nice weather becomes more and more frequent.
, from June to mid-September, is warm and sunny. The temperature in Lisbon is halfway between that recorded on the Atlantic coast (see for example the Cabo da Roca and
), where it is cool even in summer, and that of the interior (see Évora), where it is often very hot.
Typically, the temperatures are pleasant, in fact, highs don't reach 30 °C (86 °F), and lows are below 20 °C (68 °F). In addition, the breeze blows from the ocean, tempering the heat. The clarity of the air shows that we are not on the Mediterranean coasts, where summer tends to be muggier.
Sometimes, there may still be spring-like weather, a little cool, with highs around 22/23 °C (72/73 °F), especially in June.
However, there can even be hot periods due to African air masses: in these cases, the temperature can reach 36/38 °C (97/100 °F), and sometimes up to 40 °C (104 °F). Typically, these heatwaves occur from mid-June to early September, for example, the temperature reached 38 °C (100.5 °F) in early September 2016 and 40 °C (104 °F) in mid-June 2017. The record is 43.3 °C (110 °F), set in August 2018.
, from mid-September to November, is initially warm and sunny, then it gradually becomes milder, while waves of bad weather become more frequent. November is a rainy month.
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 in winter, there are cloudy periods, shorter or longer, alternating with sunny periods. However, there are on average 2,800 hours of sunshine per year.
in Lisbon is definitely cool to swim in, or a little cold, even in summer: the water temperature reaches 20.5 °C (69 °F) in August and September.
To visit Lisbon, you can choose the periods from mid-April to mid-June and from mid-September to early October. In summer, the sun usually shines and temperatures are pleasant or acceptable, but it can sometimes be very hot.
. Here are the average temperatures.
January, the coldest month of the year, is generally a mild month. The average temperature is of
11.8 °C, with a minimum of
8.8 °C and a maximum of
14.9 °C.
On the coldest nights of the month, the temperature usually drops to around
5 °C. However, it dropped to
1.6 °C in January 2009.
On the warmest days of the month, the temperature usually reaches around
18.5 °C. However, it reached
22.6 °C in January 2008.
Precipitation amounts to
110 mm, distributed over 10 days.
The day lasts on average 9 hours and 50 minutes.
There are on average 4.5 hours of sunshine per day. So, the sun shines 47% of the time.
The average humidity is 82%. Hence, the air is normally humid.
The average wind speed is of
12.7 kph.
The average sea temperature is of
15.7 °C. Therefore, the sea is cold for swimming.
February is generally a mild month. The average temperature is of
12.7 °C, with a minimum of
9.2 °C and a maximum of
16.1 °C.
On the coldest nights of the month, the temperature usually drops to around
6 °C. However, it dropped to
2.7 °C in February 2012.
On the warmest days of the month, the temperature usually reaches around
20 °C. However, it reached
23.7 °C in February 1997.
Precipitation amounts to
80 mm, distributed over 8 days.
The day lasts on average 10 hours and 50 minutes.
There are on average 5.5 hours of sunshine per day. So, the sun shines 52% of the time.
The average humidity is 78%. Hence, the air is normally humid.
The average wind speed is of
13.6 kph.
The average sea temperature is of
15.1 °C. Therefore, the sea is cold for swimming.
March is generally a very mild month. The average temperature is of
14.8 °C, with a minimum of
11.1 °C and a maximum of
18.6 °C.
On the coldest nights of the month, the temperature usually drops to around
7 °C. However, it dropped to
0.6 °C in March 2005.
On the warmest days of the month, the temperature usually reaches around
25 °C. However, it reached
29.4 °C in March 2002.
Precipitation amounts to
75 mm, distributed over 8 days.
The day lasts on average 12 hours and 0 minutes.
There are on average 6.5 hours of sunshine per day. So, the sun shines 56% of the time.
The average humidity is 73%. Hence, the air is normally humid.
The average wind speed is of
14.5 kph.
The average sea temperature is of
15.2 °C. Therefore, the sea is cold for swimming.
April is generally a very mild month. The average temperature is of
16.2 °C, with a minimum of
12.3 °C and a maximum of
20.1 °C.
On the coldest nights of the month, the temperature usually drops to around
9 °C. However, it dropped to
6.2 °C in April 1995.
On the warmest days of the month, the temperature usually reaches around
27 °C. However, it reached
30.4 °C in April 2008.
Precipitation amounts to
70 mm, distributed over 8 days.
The day lasts on average 13 hours and 20 minutes.
There are on average 8 hours of sunshine per day. So, the sun shines 58% of the time.
The average humidity is 71%. Hence, the air is normally humid.
The average wind speed is of
15 kph.
The average sea temperature is of
15.8 °C. Therefore, the sea is cold for swimming.
May is generally a warm month. The average temperature is of
18.5 °C, with a minimum of
14.4 °C and a maximum of
22.6 °C.
On the coldest nights of the month, the temperature usually drops to around
10.5 °C. However, it dropped to
8.9 °C in May 2001.
On the warmest days of the month, the temperature usually reaches around
30.5 °C. However, it reached
34.8 °C in May 2001.
Precipitation amounts to
60 mm, distributed over 5 days.
The day lasts on average 14 hours and 20 minutes. So the days are long.
There are on average 9.5 hours of sunshine per day. So, the sun shines 66% of the time.
The average humidity is 67%.
The average wind speed is of
15.6 kph.
The average sea temperature is of
16.9 °C. Therefore, the sea is cold for swimming.
June is generally a warm month. The average temperature is of
21.3 °C, with a minimum of
16.9 °C and a maximum of
25.8 °C.
On the coldest nights of the month, the temperature usually drops to around
13.5 °C. However, it dropped to
11.9 °C in June 1992.
On the warmest days of the month, the temperature usually reaches around
34 °C. However, it reached
40.2 °C in June 2017.
Precipitation amounts to
15 mm, distributed over 2 days.
The day lasts on average 14 hours and 50 minutes. So the days are long. June 21, the summer solstice, is the longest day of the year in the Northern Hemisphere.
There are on average 10 hours of sunshine per day. So, the sun shines 68% of the time.
The average humidity is 64%.
The average wind speed is of
16.4 kph.
The average sea temperature is of
18.7 °C. Therefore, the sea is very cool for swimming.
July is generally a warm to hot month. The average temperature is of
23.1 °C, with a minimum of
18.3 °C and a maximum of
27.8 °C.
On the coldest nights of the month, the temperature usually drops to around
15.5 °C. However, it dropped to
14.2 °C in July 1991.
On the warmest days of the month, the temperature usually reaches around
35.5 °C. However, it reached
40.6 °C in July 1991.
Precipitation amounts to only
0 mm, so on average it never rains in the whole month.
The day lasts on average 14 hours and 30 minutes. So the days are long.
There are on average 11.5 hours of sunshine per day. So, the sun shines 79% of the time.
The average humidity is 62%.
The average wind speed is of
18.3 kph.
The average sea temperature is of
19.8 °C. Therefore, the sea is very cool for swimming.
August, the warmest month of the year, is generally a warm to hot month. The average temperature is of
23.6 °C, with a minimum of
18.9 °C and a maximum of
28.4 °C.
On the coldest nights of the month, the temperature usually drops to around
16 °C. However, it dropped to
14.7 °C in August 2002.
On the warmest days of the month, the temperature usually reaches around
35 °C. However, it reached
43.3 °C in August 2018.
Precipitation amounts to only
5 mm, and all occurs in one day.
The day lasts on average 13 hours and 35 minutes.
There are on average 11 hours of sunshine per day. So, the sun shines 82% of the time.
The average humidity is 62%.
The average wind speed is of
17 kph.
The average sea temperature is of
20.4 °C. Therefore, the sea is cool for swimming.
September is generally a warm month. The average temperature is of
22 °C, with a minimum of
17.7 °C and a maximum of
26.3 °C.
On the coldest nights of the month, the temperature usually drops to around
14.5 °C. However, it dropped to
12.1 °C in September 1992.
On the warmest days of the month, the temperature usually reaches around
32.5 °C. However, it reached
38 °C in September 2016.
Precipitation amounts to
40 mm, distributed over 4 days.
The day lasts on average 12 hours and 25 minutes.
There are on average 8.5 hours of sunshine per day. So, the sun shines 70% of the time.
The average humidity is 66%.
The average wind speed is of
14.4 kph.
The average sea temperature is of
20.4 °C. Therefore, the sea is cool for swimming.
October is generally a warm month. The average temperature is of
19 °C, with a minimum of
15.4 °C and a maximum of
22.6 °C.
On the coldest nights of the month, the temperature usually drops to around
11.5 °C. However, it dropped to
8.7 °C in October 2018.
On the warmest days of the month, the temperature usually reaches around
28.5 °C. However, it reached
33.4 °C in October 2011.
Precipitation amounts to
115 mm, distributed over 9 days.
The day lasts on average 11 hours and 5 minutes.
There are on average 7 hours of sunshine per day. So, the sun shines 62% of the time.
The average humidity is 74%. Hence, the air is normally humid.
The average wind speed is of
13.2 kph.
The average sea temperature is of
19.7 °C. Therefore, the sea is very cool for swimming.
November is generally a very mild month. The average temperature is of
14.9 °C, with a minimum of
11.9 °C and a maximum of
18 °C.
On the coldest nights of the month, the temperature usually drops to around
8 °C. However, it dropped to
5.4 °C in November 2008.
On the warmest days of the month, the temperature usually reaches around
22.5 °C. However, it reached
25.3 °C in November 2007.
Precipitation amounts to
135 mm, distributed over 10 days.
The day lasts on average 10 hours and 5 minutes.
There are on average 5 hours of sunshine per day. So, the sun shines 52% of the time.
The average humidity is 80%. Hence, the air is normally humid.
The average wind speed is of
12.7 kph.
The average sea temperature is of
18.3 °C. Therefore, the sea is very cool for swimming.
December is generally a mild month. The average temperature is of
12.4 °C, with a minimum of
9.6 °C and a maximum of
15.2 °C.
On the coldest nights of the month, the temperature usually drops to around
5.5 °C. However, it dropped to
2.6 °C in December 2009.
On the warmest days of the month, the temperature usually reaches around
19 °C. However, it reached
21.7 °C in December 2015.
Precipitation amounts to
105 mm, distributed over 10 days.
The day lasts on average 9 hours and 30 minutes. December 21, the winter solstice, is the shortest day of the year in the Northern Hemisphere.
There are on average 4.5 hours of sunshine per day. So, the sun shines 48% of the time.
The average humidity is 84%. Hence, the air is normally humid.
The average wind speed is of
12.9 kph.
The average sea temperature is of
16.8 °C. Therefore, the sea is cold for swimming.