National Weather Service United States Department of Commerce

Back-to-Back Pacific Storms to Impact the West Coast; Heavy Snow in the Central Appalachians

Back-to-back powerful Pacific storm systems to impact the Pacific Northwest and northern California through the end of this week with heavy rain, flooding, strong winds, and higher elevation mountain snow. A strong, long-duration atmospheric river will accompany the Pacific storms, bringing excessive rainfall and flash flooding to southwest Oregon and northwest California through the week. Read More >

UV index values for the following cities:

Aberdeen, SD

Watertown, SD

Pierre, SD

Mobridge, SD

Sisseton, SD

Miller, SD

Ortonville, MN

UV Index Applications

 

 

 

About the UV Index:

The National Weather Service works with the Environmental Protection Agency, to forecast the Ultraviolet (UV) Index for the U.S.

The UV index is a measure to help you determine the effects of the sun on outdoor activities.  It is computed using forecast ozone levels, cloudiness, and elevation.  Values are effective at solar noon, which is when the sun is at its highest point of the day.  (Solar noon generally does not correspond to the clock time of 12:00 noon.)  Overexposure during days with high UV values can be harmful, both in the short term and over the long term.  Exposure to surface objects that reflect light (such as sand and water) can make the UV index even higher in such locations.

The UV Index runs on a scale of 1 to 11+:

 

UV Value and Category

Effects

1-2 
("Low")

A UV Index reading of 2 or less means low danger from the sun's UV rays for the average person:

  • You can safely enjoy being outside. Wear sunglasses on bright days. If you burn easily, cover up and use sunscreen SPF 15+.
  • In winter, reflection off snow can nearly double UV strength.

3-5
("Moderate")

A UV Index reading of 3 to 5 means moderate risk of harm from unprotected sun exposure.

  • Take precautions if you will be outside, such as wearing a hat and sunglasses and using sunscreen SPF 15+.
  • Reduce your exposure to the sun's most intense UV radiation by seeking shade during midday hours.

6-7
("High")

A UV Index reading of 6 to 7 means high risk of harm from unprotected sun exposure. Protection against sun damage is needed.

  • Protection against sun damage is needed. Wear a wide-brimmed hat and sunglasses, use sunscreen SPF 15+ and wear a long-sleeved shirt and pants when practical.
  • Reduce your exposure to the sun's most intense UV radiation by seeking shade during midday hours.

8-10
("Very High")

A UV Index reading of 8 to 10 means very high risk of harm from unprotected sun exposure. Protection against sun damage is needed. 

  • Protection against sun damage is needed. If you need to be outside during midday hours between 10 a.m. and 4 p.m., take steps to reduce sun exposure. A shirt, hat and sunscreen are a must, and be sure you seek shade.

  •  

    Beachgoers should know that white sand and other bright surfaces reflect UV and can double UV exposure.

11+
("Extreme")

A UV Index reading of 11 or higher means extreme risk of harm from unprotected sun exposure. Try to avoid sun exposure during midday hours, from 10 a.m. to 4 p.m. Apply sunscreen with an SPF of at least 30 liberally every 2 hours.

  • Protection against sun damage is needed. If you need to be outside during midday hours between 10 a.m. and 4 p.m., take steps to reduce sun exposure. A shirt, hat and sunscreen are a must, and be sure you seek shade.

  • Beachgoers should know that white sand and other bright surfaces reflect UV and can double UV exposure.

By visiting the EPA's Sunwise page at https://www.epa.gov/sunsafety , you can get UV index values for other locations by entering specific cities or ZIP codes.  You can also access nationwide maps of UV index values for the next 4 days.

UV Safety: Stay Safe in the Sun