This is the exact same way you would normally find the darkest parts of the image when you're removing any color casts from the shadow areas, but now, thanks to the Difference blend mode, these darkest areas represent the areas closest to midtone gray.
The warmest sea in Key Largo in March is 26Â°C/79Â°F, and the coldest sea temperature in March is 22Â°C/72Â°F. Average water temperature in Key Largo in March is 24Â°C/75Â°F. You can choose any other years:
Weather in Hilton Head Island in March. The average maximum daytime temperature in Hilton Head Island in March is a comfortable 20Â°C (68Â°F). There are usually 8 hours of bright sunshine each day, which represents 63% of the 12 hours of daylight. The average sea temperature in and around Hilton Head Island in March is 16Â°C (61Â°F). Expect 104mm (4.1 inches) of rainfall across the whole of March with 9 days with some rain falling. Maximum UV levels will be high (7 UV index) at midday when the skies are clear.