Heat Index Screensaver
The Heat Index screensaver is a live world map of the apparent temperature — how hot or cold it actually feels with humidity and wind — glowing blue to red across major cities, from the key-less Open-Meteo API. It's free, runs in your browser, and ESC exits.
Live preview
Press ESC to leave fullscreen. Settings are saved in your browser only.
How the Heat Index screensaver works
The saver asks Open-Meteo for the apparent (feels-like) temperature at a built-in list of major world cities, including Toronto, Vancouver, Montréal and Calgary.
Each city is plotted on a world map as a glowing dot colored from deep blue when it feels frigid to red when it feels dangerously hot.
Dots grow at the extremes — both blistering heat and biting cold — so the day's hot and cold spots stand out.
It refreshes every few minutes so the map tracks the warming and cooling through the day.
A worked example
In a summer heatwave you'll see Phoenix glaring red at a feels-like 46° while a Canadian winter night turns Calgary deep blue — the labelled hottest and coldest cities calling out the extremes.
Settings & tips
- Units switches between Celsius and Fahrenheit.
- Refresh sets how often the readings update.
- Background sets the map backdrop.
Frequently asked questions
- Is the data live?
- Yes. The feels-like temperature for every city comes live from Open-Meteo and refreshes every few minutes.
- What is apparent temperature?
- It's how hot or cold it actually feels once humidity, wind and sun are factored in — often quite different from the raw thermometer reading.
- Does it need a key?
- No. Open-Meteo is free and key-less; the saver only needs an internet connection.
- Which cities are shown?
- A built-in spread of major world cities across every continent, including several Canadian cities.
- Is it free?
- Yes — free, no download, in your browser.