Heat & Weather Tools & Calculators
Free, practical tools for beating the heat — check the dog days, gauge the heat index, read the humidity, track the sun and UV, and convert any temperature to stay safe and comfortable all summer.
Dog Days of Summer Calculator
Check whether any date falls in the dog days — July 3 to August 11, the 40 hottest days of the Northern-Hemisphere year — and see how far through the heatwave stretch you are
Heat Index Calculator
Get the 'feels like' heat index from air temperature and humidity using the National Weather Service equation — the apparent temperature in °F and °C, plus its heat-risk category
Humidity Comfort Calculator
Turn temperature and relative humidity into a dew point and a plain-language comfort level, from dry to oppressive, so you know exactly how muggy and sticky the air feels
Sunrise & Sunset Calculator
Estimate day length, sunrise, and sunset in solar time from your latitude and the day of the year — see how the summer sun stretches daylight at your latitude
Temperature Converter
Convert any temperature between Celsius, Fahrenheit, and Kelvin instantly — enter one value and see all three scales at once, perfect for reading any weather forecast
UV Index Calculator
Enter today's UV index for the risk category, an estimated time to sunburn for fair skin, and the sunscreen SPF to reach for — a fast sun-safety check for bright days