Hotter still is the core. In the sun this is thought to be 10 - 20 million degrees. These temperatures are due to the pressure caused by gravity trying to compress the star. It has to be this temperature for fusion of hydrogen to take place. Once fusion starts in a young star this adds to the temperature to ensure that fusion continues.
Weather in Lisbon in September. The average maximum daytime temperature in Lisbon in September is a warm 27Â°C (81Â°F) with low heat & humidity. There are usually 9 hours of bright sunshine each day, which represents 68% of the 12 hours of daylight. The average sea temperature in and around Lisbon in September is 19Â°C (66Â°F). Expect 26mm (1.0 inches) of rainfall across the whole of September with 6 days with some rain falling. Maximum UV levels will be high (6 UV index) at midday when the skies are clear.
Summer temperatures are warm and sometimes hot, while winters are mild and damp. Lisbon sees a lot of sunshine (over 3300 hrs per year) and about 100 days of rain a year. The Atlantic Ocean strongly influences the weather in Lisbon, primarily as a consequence of the nearby flow of the Gulf stream. These currents ensure that the coastal city of Lisbon does not experience the extreme temperatures that can occur in central Portugal and Spain. While on average about 600 mm, or 24 inches, of rain falls annually in Lisbon, the precipitation is spread out over 100 days of the year, so there are rare days without at least some sunshine. Like anywhere in the world, weather varies year on year in Lisbon and averages don't tell the whole picture.