What is the UV Index and how to protect yourself

The UV index is an international measure that tells you how strong the sun's ultraviolet radiation is at a given time and place. The higher the value, the greater the risk of damage to your skin and eyes, and the less time it takes to burn. It is a simple tool that helps you decide when and how to protect yourself.

Ultraviolet radiation cannot be seen, and you do not feel it as heat, which makes it easy to underestimate. You can get sunburned on a cool or cloudy day if the UV index is high. That is why it is worth checking the UV forecast just as you check the temperature. At Meteo Info Online we source this data from Open-Meteo.

The UV index scale

The UV index is given as a number that usually runs from 0 to above 11. The scale is grouped into risk levels with a colour code recognised worldwide:

0 to 2 (low, green): minimal risk. You can safely be outdoors.
3 to 5 (moderate, yellow): seek shade around midday and use protection if you will be out for a while.
6 to 7 (high, orange): skin and eyes are damaged quickly. Protection is needed.
8 to 10 (very high, red): take every precaution and avoid the midday sun.
11 or more (extreme, purple): maximum risk. Unprotected skin can burn within minutes.

What makes the UV index rise

Several factors influence how high the index gets in your area. Knowing them helps you plan ahead:

Time of day: the peak occurs around solar noon, usually between 10 a.m. and 4 p.m.
Time of year: it is strongest in summer and near the solstice.
Latitude: in tropical and equatorial regions the index stays high almost all year.
Altitude: radiation increases noticeably in the mountains, rising by about 10 % every 1000 metres.
Reflective surfaces: snow, sand and water bounce the rays back and increase your exposure.
Clouds: they cut radiation somewhat, but thin clouds let much of the UV through.

How to protect yourself by level

From an index of 3 upward it is worth taking action. Protection does not rely on a single step but on combining several:

Sunscreen: use a broad-spectrum product with SPF 30 or higher. Apply it 15 to 20 minutes before going out and reapply every two hours, and after sweating or swimming.
Seek shade: especially during the middle hours of the day. A useful rule: if your shadow is shorter than your height, the sun is strong.
Clothing and accessories: long-sleeved shirts, a wide-brimmed hat and UV-filtering sunglasses protect better than sunscreen alone.
Protect your eyes: radiation harms your sight too, so UV-rated sunglasses matter.

Who is most at risk

Everyone should protect themselves, but some people are more sensitive to ultraviolet radiation:

Babies and young children, whose skin is more delicate.
People with fair skin, freckles or who burn easily.
Those who work or play sports outdoors for many hours.
People with many moles or a family history of skin cancer.
Anyone taking certain medications that increase sensitivity to the sun.

Excessive sun exposure builds up over a lifetime and is the leading cause of premature skin ageing and skin cancer. The good news is that almost all of that damage can be avoided with simple habits. Check the UV index for your city before planning outdoor activities and match your protection to the level of the day.