UV Index Today
Real-time solar radiation monitoring
Frequently Asked Questions
What exactly is the UV Index?
The Global Solar UV Index (UVI) is a standard measurement of the strength of sunburn-producing ultraviolet (UV) radiation at a particular place and time. It was developed by the WHO to help people protect themselves from UV rays, which are invisible and can cause skin cancer.
Does a high UV index mean it is hot outside?
No. UV radiation is not the same as heat. You can have a high UV index on a cool, breezy day or even a cold day with snow. UV rays are energy, not temperature. You cannot feel them until the damage (sunburn) has already started.
Do I need sunscreen on cloudy days?
Yes. Up to 80% of UV rays can pass through light clouds. Sometimes, clouds can even increase UV levels by reflecting the rays. Always check the index rather than looking at the sky.
When is the UV radiation at its peak?
UV radiation is strongest when the sun is highest in the sky, typically between 11:00 AM and 4:00 PM. During these hours, the sun's rays have the shortest distance to travel through the atmosphere.
How often should I reapply sunscreen?
Regardless of the UV index, you should reapply sunscreen every two hours, or more frequently if you are swimming, sweating, or toweling off. Most people apply too little; aim for about a teaspoon for each limb.
Is there any benefit to UV radiation?
Small amounts of UV radiation are essential for the production of Vitamin D in the body. However, for most people, 5–15 minutes of casual sun exposure on the hands, face, and arms 2–3 times a week is sufficient.