National Ultrviolet Index (UVI)

Valid: DEC 12 2017 at Solar Noon
What is the Ultrviolet Index?

The Ultrviolet Index is a forecast of the probable intensity or amount of skin damaging radiation expected to reach the surface of the earth at the solar noon hour (11:30-12:30 local standard time or 12:30-1:30 local daylight time.) The UV Index can range from 0 at nighttime to as high as 15 in the Tropics under clear skies.

Here's the key to the UV Index; the higher the UV Index the greater the threat is to your skin and eyes. At the same time the higher the UV Index, the lesser the time it will take to damage human skin. How much UV radiation is needed to actually damage the skin is dependant on several factors. But in general the darker your skin is, (that is the more melanin one has in their skin) the longer (or the more UV radiation) it takes to cause erythema (skin reddening).

Below is a look up chart where you can cross check your propensity to burn versus the UV Index. For those who always burn and never tan the times to burn are relatively short compared to those who almost always tan.

National UVI Summery Map
UVI Summery By City
Albuquerque, NM

Ultrviolet Index in Albuquerque, NM: Low (3)
Anchorage, AK

Ultrviolet Index in Anchorage, AK: Minimal (0)
Atlantic City, NJ

Ultrviolet Index in Atlantic City, NJ: Minimal (1)
Atlanta, GA

Ultrviolet Index in Atlanta, GA: Minimal (2)
Baltimore, MD

Ultrviolet Index in Baltimore, MD: Minimal (1)
Billings, MT

Ultrviolet Index in Billings, MT: Minimal (1)
Bismarck, ND

Ultrviolet Index in Bismarck, ND: Minimal (1)
Boise, ID

Ultrviolet Index in Boise, ID: Minimal (1)
Boston, MA

Ultrviolet Index in Boston, MA: Minimal (0)
Buffalo, NY

Ultrviolet Index in Buffalo, NY: Minimal (0)
Burlington, VT

Ultrviolet Index in Burlington, VT: Minimal (0)
Charleston, WV

Ultrviolet Index in Charleston, WV: Minimal (1)
Charleston, SC

Ultrviolet Index in Charleston, SC: Low (3)
Cheyenne, WY

Ultrviolet Index in Cheyenne, WY: Minimal (2)
Chicago, IL

Ultrviolet Index in Chicago, IL: Minimal (1)
Cleveland, OH

Ultrviolet Index in Cleveland, OH: Minimal (1)
Concord, NH

Ultrviolet Index in Concord, NH: Minimal (0)
Dallas, TX

Ultrviolet Index in Dallas, TX: Low (3)
Denver, CO

Ultrviolet Index in Denver, CO: Minimal (2)
Des Moines, IA

Ultrviolet Index in Des Moines, IA: Minimal (1)
Detroit, MI

Ultrviolet Index in Detroit, MI: Minimal (1)
Dover, DE

Ultrviolet Index in Dover, DE: Minimal (1)
Hartford, CT

Ultrviolet Index in Hartford, CT: Minimal (0)
Honolulu, HI

Ultrviolet Index in Honolulu, HI: Moderate (6)
Houston, TX

Ultrviolet Index in Houston, TX: Low (4)
Indianapolis, IN

Ultrviolet Index in Indianapolis, IN: Minimal (1)
Jackson, MS

Ultrviolet Index in Jackson, MS: Low (3)
Jacksonville, FL

Ultrviolet Index in Jacksonville, FL: Low (3)
Las Vegas, NV

Ultrviolet Index in Las Vegas, NV: Minimal (2)
Little Rock, AR

Ultrviolet Index in Little Rock, AR: Minimal (2)
Los Angeles, CA

Ultrviolet Index in Los Angeles, CA: Low (3)
Louisville, KY

Ultrviolet Index in Louisville, KY: Minimal (1)
Memphis, TN

Ultrviolet Index in Memphis, TN: Minimal (2)
Miami, FL

Ultrviolet Index in Miami, FL: Moderate (5)
Milwaukee, WI

Ultrviolet Index in Milwaukee, WI: Minimal (1)
Minneapolis, MN

Ultrviolet Index in Minneapolis, MN: Minimal (1)
Mobile, AL

Ultrviolet Index in Mobile, AL: Low (3)
New Orleans, LA

Ultrviolet Index in New Orleans, LA: Low (4)
New York, NY

Ultrviolet Index in New York, NY: Minimal (0)
Norfolk, VA

Ultrviolet Index in Norfolk, VA: Minimal (2)
Oklahoma City, OK

Ultrviolet Index in Oklahoma City, OK: Minimal (2)
Omaha, NE

Ultrviolet Index in  Omaha, NE: Minimal (1)
Philadelphia, PA

Ultrviolet Index in Philadelphia, PA: Minimal (1)
Phoenix, AZ

Ultrviolet Index in Phoenix, AZ: Low (3)
Pittsburgh, PA

Ultrviolet Index in Pittsburgh, PA: Minimal (1)
Portland, ME

Ultrviolet Index in Portland, ME: Minimal (0)
Portland, OR

Ultrviolet Index in Portland, OR: Minimal (1)
Providence, RI

Ultrviolet Index in Providence, RI: Minimal (0)
Raleigh, NC

Ultrviolet Index in Raleigh, NC: Minimal (2)
Salt Lake City, UT

Ultrviolet Index in Salt Lake City, UT: Minimal (2)
San Francisco, CA

Ultrviolet Index in San Francisco, CA: Minimal (2)
San Juan, PR

Ultrviolet Index in San Juan, PR: High (7)
Seattle, WA

Ultrviolet Index in Seattle, WA: Minimal (1)
Sioux Falls, SD

Ultrviolet Index in Sioux Falls, SD: Minimal (1)
St. Louis, MO

Ultrviolet Index in St. Louis, MO: Minimal (1)
Tampa, FL

Ultrviolet Index in Tampa, FL: Low (4)
Washington, DC

Ultrviolet Index in Washington, DC: Minimal (1)
Wichita, KS

Ultrviolet Index in Wichita, KS: Minimal (2)
Protecting Yourself from Ultraviolet (UV) Radiation

The EPA has devised general guidelines as far as what to do to protect yourself from overexposure to UV radiation. These are shown in the table below.

Exposure Category UV Index Protective Actions
Minimal 0, 1, 2 Apply skin protection factor (SPF) 15 sun screen.
Low 3, 4 SPF 15 & protective clothing (hat)
Moderate 5, 6 SPF 15, protective clothing, and UV-A&B (sun glasses).
High 7, 8, 9 SPF 15, protective clothing, sun glasses and make attempts to avoid the sun between 10am to 4pm.
Very High 10+ SPF 15, protective clothing, sun glasses and avoid being in the sun between 10am to 4pm.
The Dangers of Ultraviolet (UV) Radiation

Ultraviolet (UV) radiation is a specific part of the sun's entire spectrum of wavelengths. UV radiation can be further sub-divided into three parts. UV-C is characterized by wavelengths less than 280 nm. Although highly dangerous to plants and animals, this part of the UV spectrum is completely absorbed by stratospheric ozone and does not reach the earth's surface. UV-B ranges in wavelengths between 280 and 320 nm. Ozone absorbs much of the shorter wavelength radiation, but this absorption weakens as 320 nm is approached. Plants and animals are particularly affected by this part of the UV spectrum. UV-B effects to humans are reddening of the skin (erythema) and reduction of vitamin-D synthesis in the short term, development of skin cancer, cataracts and suppression of the immune system in the long term. The wavelengths of UV-A radiation range between 320 and 400 nm. Ozone absorbs very little of this part of the UV spectrum. UV-A radiation is needed by humans for the synthesis of vitamin-D; however, too much UV-A causes photoaging (toughening of the skin), suppression of the immune system and, to a lesser degree, reddening of the skin, and cataract formation.

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