Rates an outdoor spa or hot tub from 6am to 9pm, evenings included. GoDay finds the best 2 hours of each day, weighing warmth first, then wind chill and rain.
Also on the page, but not in the score: UV, daylight.
A thunderstorm holds the score at 2: get out of the water when there is lightning. Air under 10°C (50°F) holds it at 2, under 14°C (57°F) at 4, and under 18°C (64°F) at 6.
Warm, still and dry: 22°C (72°F) or more with little wind. Plenty of people love a spa on a cold night, but GoDay rates the weather for sitting out in, so cold nights score lower.
Yes. Wind strips heat off your head and shoulders, so a breezy 18°C feels far colder than a still one. Past 35 km/h (22 mph) GoDay rates it windy.
No. Water and lightning don't mix, so any thunderstorm drops the score to 2.