A UV index reading of 8 to 10 means very high risk of harm from unprotected sun exposure.
Take extra precautions because unprotected skin and eyes will be damaged and can burn quickly.
Minimize sun exposure between 10 a.m. and 4 p.m. If outdoors, seek shade and wear sun protective clothing,
a wide-brimmed hat, and UV-blocking sunglasses. Generously apply broad spectrum SPF 30+ sunscreen
every 2 hours, even on cloudy days, and after swimming or sweating.
Bright surfaces, such as sand, water, and snow, will increase UV exposure.
On the ground:
Raises dust and loose paper; small branches are moved.
On the sea:
Small waves, becoming larger; fairly frequent white horses.
On the ground:
Small trees in leaf begin to sway; crested wavelets form on inland waters.
On the sea:
Moderate waves, taking a more pronounced long form; many white horses are formed.
On the ground:
Wind felt on face; leaves rustle; ordinary vanes moved by wind.
On the sea:
Small wavelets, still short, but more pronounced. Crests have a glassy appearance and do not break.
On the ground:
Large branches in motion; whistling heard in telegraph wires; umbrellas used with difficulty.
On the sea:
Large waves begin to form; the white foam crests are more extensive everywhere.
On the ground:
Leaves and small twigs in constant motion; wind extends light flag.
On the sea:
Large wavelets. Crests begin to break. Foam of glassy appearance. Perhaps scattered white horses.
On the ground:
Whole trees in motion; inconvenience felt when walking against the wind.
On the sea:
Sea heaps up and white foam from breaking waves begins to be blown in streaks along the direction of the wind.
Power systems: Weak power grid fluctuations can occur.
Spacecraft operations: Minor impact on satellite operations possible.
Other systems: Migratory animals are affected at this and higher levels;
aurora is commonly visible at high latitudes (northern Michigan and Maine).