The Simple Answer :   The color of a star's visible light indicates its surface temperature: a relatively cool star glows red (longer wavelength), and very hot ones glow â¦ bluish-white or even blue (shorter wavelengths).
Over the course of the year, the temperature in Shetland typically varies from 37Â°F to 59Â°F and is rarely below 30Â°F or above 63Â°F. The warm season lasts for 82 days, from June 24 to September 14, with an average daily high temperature above 55Â°F. The hottest day of the year is August 6, with an average high of 59Â°F and low of 52Â°F. The cool season lasts for 133 days, from November 26 to April 8, with an average daily high temperature below 46Â°F.
Weather in Cape Town in September. The average maximum daytime temperature in Cape Town in September is a comfortable 18Â°C (64Â°F). There are usually 7 hours of bright sunshine each day, which represents 62% of the 12 hours of daylight. The average sea temperature in and around Cape Town in September is 15Â°C (59Â°F). Expect 96mm (3.8 inches) of rainfall across the whole of September with 11 days with some rain falling. Maximum UV levels will be high (6 UV index) at midday when the skies are clear.