UV-INDEKS

What happens the second you open it

You install the app, grant location access, and the home screen shows a number. That number is the UV index for your exact spot. For a user in Copenhagen on a summer afternoon, the app might show a 5. But the real test comes when you add a second location — say, a beach town in Spain. The app pulls data for both places simultaneously. The cloud cover slider lets you see how overcast skies would drop that 5 down to a 2. This is not a generic weather widget. It is a focused radiation meter.

The onboarding process asks for no account. No email. No password. You pick your skin type from a simple guide — fair, medium, or dark — and the app calculates how many minutes you can stay out before burning. A fair-skinned person seeing a UV index of 7 gets a warning: sunburn in 15 minutes. The same person seeing a 3 gets a much longer window. This immediate personalization is what separates it from a basic forecast. The app does not just tell you the number; it tells you what the number means for your skin.

Location permissions are required for the current-position forecast. If you turn them off, the app falls back to a manual city search. The changelog for version 5.2.1 specifically fixes a bug where adding cities failed when location permissions were disabled. This tells you that the app's core logic depends heavily on knowing where you are, but the developers have built a fallback that actually works now.

How cloud cover and skin type fight each other

The app pulls UV data from the Danish Meteorological Institute and other sources. It then applies a cloud-cover adjustment. If the forecast says UV 6 but the sky is 80% overcast, the app reduces the effective UV to around 2 or 3. This is where the original analysis kicks in: the cloud adjustment and the skin type guide are not separate features. They work together to produce a safe-exposure window. For a medium-skin user, the app might say "UV 4, clouds reduce to 2, you can stay out for 2 hours." But if you switch to a different location with the same UV but no clouds, the window shrinks to 45 minutes.

This interaction is not spelled out on the Play Store page. The page lists "cloud cover impact" and "skin type guide" as separate bullet points. In practice, the app combines them into a single risk assessment. A user in Denmark planning a beach day in Spain can save both locations and compare the adjusted UV values side by side. The app shows the raw forecast, the cloud-adjusted number, and the recommended sun protection factor all on one screen. This workflow is the real reason people keep the app installed.

Compared to a generic UV widget, this app gives you a reason to trust the number. The skin type guide is not a gimmick — it uses the Fitzpatrick scale, which dermatologists actually use. The app tells you, based on your skin type, when to reapply sunscreen and when to seek shade. This is not a feature you find in most weather apps.

The real-world performance: ads, bugs, and what actually breaks

The app has no ads. That is unusual for a free app. The Danish Cancer Society funds it, so there is no commercial pressure to show banners or interrupt the user. This makes the experience clean but also means updates come slowly. The version history shows gaps of months between releases. The current version, 5.2.1, was released in June 2026. The previous version, 3.3.2, was from 2025. That is a big jump, which suggests the developers overhauled something significant.

User complaints cluster around accuracy. One reviewer in a hot, cloudless location reported the app showing a UV index of 3 when it should have been 8 or 9. Another user in Denmark saw a warning for UV 9, which is practically impossible at that latitude. These are not isolated issues. The app relies on external data sources, and when those sources are wrong, the app is wrong. There is no manual override. You cannot tell the app "it is sunnier than that."

Background behavior is another pain point. Some users report the app does not update the widget unless you open it. The widget, if you use one, might show yesterday's value. This undermines the "daily updates" promise. The app does not aggressively fetch data in the background, which saves battery but means you have to remember to refresh it manually. For a sun-safety tool, that is a real limitation.

Location permission bug and the fallback that finally works

The version 5.2.1 changelog, in Danish, says: "Denne opdatering løser en række mindre problemer bland andet med at tilføje byer når appen ikke har lokations beføjelser er slået fra." That translates to: this update fixes a number of minor issues, including adding cities when location permissions are turned off. This is a specific technical fix. Before this update, if you denied location access, the app could not add new cities to your saved list. You were stuck with the default location or nothing. Now, you can manually search and save cities even with permissions off.

This matters because many users do not want to share their precise location with a weather app. The fix means the app respects that choice. You can still get forecasts for Copenhagen, Barcelona, or any other city you type in. The app does not force you to grant location. It asks once and then works with whatever you give it. The fallback is not perfect — you lose the "current position" automatic update — but it is functional.