Summers in Lisbon are warm but comfortable. Temperatures rarely get above 30 degrees Celsius, or the mid-80s Fahrenheit. During the evening, temperatures generally stay in the high teens on the Celsius scale, or the low 60s on the Fahrenheit scale. Rainfall in Lisbon is the lightest in the summer months. In June, the average high is 26 degrees Celsius, or 79 degrees Fahrenheit, and the average low is 16 degrees Celsius, or 61 degrees Fahrenheit. July is slightly warmer, with an average high of 28 degrees Celsius, or 82 degrees Fahrenheit, and an average low of 18 degrees Celsius, or 64 degrees Fahrenheit. August is the warmest month, with an average high of 29 degrees Celsius, or 84 degrees Fahrenheit, and the average low is the same as July. The average rainfall amount for each of the three months is less than a centimeter, or less than half an inch.
Fall in Lisbon is mild but a bit wetter than summer, with the rainy season beginning in October. September is still warm, with an average high of 27 degrees Celsius, or 81 degrees Fahrenheit, and an average low of 17 degrees Celsius, or 63 degrees Fahrenheit. October is cooler, with an average high of 22 degrees Celsius, or 72 degrees Fahrenheit, and an average low of 15 degrees Celsius, or 59 degrees Fahrenheit. In November, the average high is 17 degrees Celsius, or 63 degrees Fahrenheit, and the average low is 12 degrees Celsius, or 54 degrees Fahrenheit. Rain is still light in September, with an average rainfall of 2.75 centimeters, or about an inch, but October and November both see average rainfalls close to 10 centimeters, or about 4 inches.
Winter is the heart of Lisbon's rainy season, but the temperatures still remain comfortable. December has an average high of 15 degrees Celsius, or 59 degrees Fahrenheit, and the low is 10 degrees Celsius, or 50 degrees Fahrenheit. January is the coldest month, with an average high of 14 degrees Celsius, or 57 degrees Fahrenheit, and a low of 8 degrees Celsius, or 46 degrees Fahrenheit. February is about the same, with an average high of 16 degrees Celsius, or 61 degrees Fahrenheit, and a low of 9 degrees Celsius, or 48 degrees Fahrenheit. Rainfall averages hover around 10 centimeters, or about 4 inches, in December and January, and February is a bit drier, with a rainfall average or about 6 centimeters, or about 2.5 inches.
Spring in Lisbon ushers in the end of the rainy season and pleasant temperatures. In March, the average high is 18 degrees Celsius, or 64 degrees Fahrenheit, and the low is 11 degrees Celsius, or 52 degrees Fahrenheit. April is slightly warmer, with a high of 19 degrees Celsius, or 66 degrees Fahrenheit, and the average low is the same as in March. The average high warms up to 22 degrees Celsius, or 72 degrees Fahrenheit, in May, and the average low is 14 degrees Celsius, or 57 degrees Fahrenheit. The average rainfall for the three months is around 5 centimeters, or about 2 inches.
Lisbon is prone to occasional bouts of extreme weather. The 2003 European heat wave, for example, pushed temperatures near 40 degrees Celsius, or above 100 degrees Fahrenheit. Snow and below-freezing temperatures are rare but not without precedent. Even more rarely, Lisbon has been known to have brushes with tropical cyclones. In 2005, Hurricane Vince made landfall as a tropical depression on the Iberian peninsula near Huelva, Spain, although it was little more than a rain event.
