The UV index is an international standard measurement of how strong the ultraviolet (UV) radiation from the sun is at a particular place on a particular day. Its purpose is to help people to effectively protect themselves from UV light, which causes sunburns, eye damage such as cataracts, skin aging, and skin cancer (see the section health effects of ultraviolet light). Public-health organizations recommend that people protect themselves (for example, by wearing sunscreen and a hat) when the UV index is 3 or higher; see the table below for complete recommendations.

Description

---

The index has a scale from 1, indicating a very weak sun, to 11, indicating an extremely strong sun. An index of 0 is theoretically possible, but unlikely to actually occur, as is an index greater than 11. The numbers are directly related to the amount of UV radiation reaching the surface of the earth, measured in W/m².

The UV index announced in weather forecasts is a prediction of how strong the actual UV intensity will be at the sun's highest point in the day, which typically occurs during the four-hour period surrounding solar noon. The prediction is made by a computer model that accounts for the effects of altitude and inclimate weather (clouds), which increase or decrease, respectively, the amount of UV radiation that will reach the surface. The calculations are weighted in favor of the UV wavelengths that human skin is most sensitive to. Providing the public with an easy-to-understand daily forecast of UV intensity is the main purpose of the UV index.

More on [ UV index ]

The Weather Channel: National Weather Outlook

Current Weather Conditions Across The 48 Contiguous United States
Thu, 04 Sep 2008 20:44:05 -0400
Hanna on the Move. For more details...
Your National Forecast Summary
Fri, 18 Apr 2008 11:14:06 -0400
Midwest - A storm system will ride northeastward from the Plains to the Great Lakes over the next couple of days. Rain and ... South - Weather conditions across the South will deteriorate from west to east across the South over the next couple of days ... Northeast - It seems like spring has finally sprung across the Northeast. Today will feature warm temperatures some of the warmest so ... West - Much of the Northwest will turn downright COLD as some wintry weather conditions lock in on a deep trough of ... For more details...
Video: Your 3-Day National Weather Forecast
Thu, 04 Sep 2008 20:44:05 -0400
Watch what the experts at The Weather Channel ® have to say about the weather trends in the United States for the next 3-days.
Severe Weather Alerts Across The Nation
Thu, 04 Sep 2008 20:44:05 -0400
Arkansas-California-Delaware-District Of Columbia-Florida-Georgia-Guam-Hawaii-Illinois-Indiana-Kansas-Louisiana-Maryland-Michigan-Mississippi-Missouri-Montana-New Jersey-North Carolina-Northern Mariana Islands-Oklahoma-Pennsylvania-South Carolina-Texas-Utah-Virginia-Washington-Wisconsin-Wyoming. For more details...
Airport Impact Map
Thu, 04 Sep 2008 20:44:05 -0400
A visual representation of possible weather-related delays at 24 major airports across the United States including Chicago's O'Hare, Boston's Logan, Atlanta's Hartsfield-Jackson, Dallas/Fort Worth Int', and Los Angeles Int'l. For more details...
ADV: Take the Weather with You
Thu, 04 Sep 2008 20:44:05 -0400
The Weather Channel® understands that you need access to weather information on the go. Whether you're a business traveler or an avid weekend golfer, our mobile products and services will keep you prepared for anything Mother Nature has in store. For more details...

AccuWeather.com Weather Headlines

Hanna Stalks East Coast
Tropical Storm Hanna doesn't look too healthy right now, does it? The storm has had to deal with a hostile environment all week, and that's a good thing.
Threat of a Direct Hit
Hanna will mature into a hurricane Friday, but by landfall, it's unlikely to be any stronger than a Category 2 storm. The threat of a direct hit is highest
Hanna's Weekend Impact
Hanna will make landfall on the North Carolina coastline as a Category 1 or 2 hurricane late Friday night or early Saturday. The storm will produce a 5- to
Rainfall from Hanna
Hanna will will charge up the East Coast this weekend producing wind and rain from the Carolina coast to New England. Heaviest rains from the storm will
Hanna's Storm Surge
Hanna will strengthen into a Category 1 hurricane Thursday night and Friday and could be a Category 2 storm when it reaches the North Carolina coast. That
Ike a Formidable Storm
Hurricane Ike became a formidable Category 4 storm Wednesday night with peak winds around 140 mph. The storm will remain quite powerful as it heads toward

Subscribe to Weather RSS feed