What Is the UV Index?
The UV Index is an internationally standardised scale that measures the strength of sunburn-causing ultraviolet radiation reaching the ground at a given place and time.
The scale starts at 0 and is open-ended, though values above 11 are all grouped as “Extreme”. In practice, most places see values between 0 and 12, though high-altitude tropical locations can exceed 20.
The number represents the peak UV intensity for the day, which typically occurs around solar noon.
UV Index Levels
| UV Index | Level | What to Do |
|---|---|---|
| 0–2 | Low | Minimal risk. Sunglasses on bright days. |
| 3–5 | Moderate | Wear sunscreen. Cover up during midday. |
| 6–7 | High | Seek shade during midday hours. Sunscreen and protective clothing recommended. |
| 8–10 | Very High | Minimise sun exposure. Unprotected skin can burn quickly. |
| 11+ | Extreme | Avoid being outside during midday. Unprotected skin and eyes can burn in minutes. |
At a UV index of 3 or above, you should be taking precautions. How quickly you burn depends on your skin type, but unprotected skin can burn within 45 minutes at moderate levels and in under 10 minutes at very high levels.
What Affects UV Levels?
The UV index isn’t just about how sunny it looks outside. Several factors influence how much UV radiation reaches you:
Time of day — UV is strongest in the four hours around solar noon (roughly 10am–2pm, or 11am–3pm during daylight saving). Early morning and late afternoon are significantly lower risk.
Season — Summer UV levels can be several times higher than winter in mid-latitudes. Near the equator, UV stays high year-round.
Altitude — UV increases roughly 6–10% per 1,000 metres of elevation. Mountain locations and ski resorts see significantly higher levels.
Cloud cover — Overcast skies reduce UV, but not as much as you’d think. Thin or broken cloud can still let through most of the UV radiation. Scattered clouds can even briefly intensify UV through reflection.
Surface reflection — Fresh snow reflects most UV back at you, effectively doubling your exposure. Sand and water reflect less, but still add to your total dose. Grass reflects very little.
Latitude — The closer to the equator, the higher the UV. The sun’s rays travel a shorter path through the atmosphere, meaning less UV is filtered out.
Sunscreen and Protection Tips
- At UV 3 or above, wear broad-spectrum SPF 30+ sunscreen on exposed skin.
- Apply 15–30 minutes before going outside.
- Reapply every two hours, and immediately after swimming or sweating.
- Wear sunglasses, a hat, and protective clothing — especially during midday hours.
- Clothing with a UPF (Ultraviolet Protection Factor) rating of 50 blocks 98% of UV rays — more reliable than sunscreen alone.
- If your shadow is shorter than your height, the sun is high enough for strong UV.
How Airpult Shows UV Index
Airpult displays the current UV index for your location on the forecast page, with a colour-coded scale from green (low) through yellow, orange, and red to purple (extreme). Each level includes a quick protection recommendation so you know at a glance what precautions to take. Find a location to check the UV index now.