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.
1 Overnight temperatures are generally warm with an average low of 20.5 Â°C (68.9 Â°F). 2  The variation/ range of daily mean temperatures in September is 7.8 Â°C (14 Â°F).  The weather in September is arid with scarcely any rain. A feeble 7.1mm (0.3in) of fluid is dropped across an average of 2 days.