The UV Index plots are based on ground-based measurements by Brewer spectrophotometers carried out by the Science and Technology Branch. The actual measurements are indicated by red dots and a red line. Estimates of UV Index for clear sky no-snow conditions and “normal” pre-1980 total ozone values are shown by a blue line. Estimates of UV Index for clear sky conditions and today’s total ozone values are shown by a magenta line (if available and not covered). If today’s ozone is equal to normal the magenta line will cover the blue line.
The time is shown as both local (in a time zone) and solar (the sun is in its highest position over the horizon exactly at noon).
The plots are updated every five minutes. You need to click on “Refresh” to see the updates.
WARNING: The data are processed in near real-time, have not been fully validated, and are preliminary.