A UV index reading of 3 to 5 means moderate risk of harm from unprotected sun exposure.
Stay in shade near midday when the sun is strongest. If outdoors, 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:
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.
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).
A UV index reading of 0 to 2 means low danger from the sun's UV rays for the
average person.
Wear sunglasses on bright days. If you burn easily, cover up and use broad spectrum SPF 30+ sunscreen.
Bright surfaces, such as sand, water, and snow, will increase UV exposure.
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:
Raises dust and loose paper; small branches are moved.
On the sea:
Small waves, becoming larger; fairly frequent white horses.