When are UV rays at their strongest?

First published June 2017; updated May 2020

What is Ultraviolet (UV) Radiation?

UV radiation in sunlight damages our skin. UV radiation cannot be seen or felt (infrared radiation causes heat, not UV). It can damage skin on cool, cloudy days and hot sunny days!

UV radiation comes directly from the sun and is influenced by many factors including

  • Latitude
  • Time of the day
  • Time of year
  • Altitude
  • Reflection

What is the UV Index?

The Global solar UV index is a scale that was developed by the World Health Organisation which measures the UV radiation level at the surface of the earth and gives indication of the potential for sun damage. The UV index ranges from zero upwards – the higher the UV index the greater the risk.

Whenever the UV index reaches 3 and above, sun protection is required because of skin and eye damage. UV index levels reach their peak in the middle of the day so extra care should be taken between 11:00am-3:00pm. The UV index is available on Met Eireann’s website.

Next article: How long before going out in the sun should I apply sunscreen?

For more information on how to Protect & Inspect™ against Melanoma Skin Cancer visit our information and resources page.