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 20.2 Â°C (68.4 Â°F). 2  In September the range/ variation of daily average temperatures is 6.5 Â°C (11.7 Â°F).  The weather in September is very slightly soggy with occasional rain. Around 179.8mm (7.1in) of H2O accrues across an average of 13 days.