SunMate: UV Index & Sunscreen

Sunlight isn’t the problem. The dose is.

SunMate turns the live UV index into the one thing you actually want to know: how long your skin can stay out today. Pick your skin type once, or let four quick questions pick it, and you get a burn time for right now and for any hour you’re planning around. Sun protection without writing off the afternoon.

Log your sunscreen and that time stretches while the SPF holds. The reapply reminder is timed off the UV and your skin, so it doesn’t just count down two hours and beep.

Sun is also how your body makes vitamin D, and SunMate works out roughly how much your skin type needs for it. A running sun budget shows how much UV your skin has already taken, so you can get into the shade before it’s too much.

WHAT YOU GET

☀️ Live UV index and the day’s curve. Hour by hour, clouds included, in the WHO colors or a color-blind palette.
⏱️ Your burn time for right now, in the sun or in the shade.
🧴 Tap once when you put sunscreen on, log the SPF, and the reapply reminder sets itself.
⛱️ Tap when you head out, say whether you’re in the shade or on snow, sand or water, and a sun budget ring fills the longer you stay. It speaks up when it’s getting close.
💊 A vitamin D estimate that only counts while the sun is high enough to make any. When winter shuts that window, it says until when.
📅 The 3-day outlook: a UV forecast with each day’s peak, plus alerts and a morning briefing so a harsh afternoon isn’t a surprise.
👪 Separate reapply reminders for everyone in the household. Kids get shorter ones.
📱 Widgets you design for the home and lock screen: light or dark, solid or see-through, and the home-screen one carries a sunscreen button. Saved places keep their own UV and their own time zone.

IT SHOWS ITS WORK

No phone can measure UV, so every number here is computed, and SunMate says what from. The index is an hourly NOAA-sourced forecast from currentuvindex.com, with the forecast cloud cover already in it. The cloudless reference is worked out on your phone, from the NOAA solar equations, van Heuklon’s ozone climatology and Madronich’s clear-sky relation. Burn time, the sun budget and the vitamin D estimate are arithmetic on the CIE erythema weighting against your skin type’s MED. One screen in the app lays out every model and where it stops being reliable.

No account, no ads, no tracking. The UV index, your burn time, the sunscreen log, vitamin D and today’s sun budget are free. SunMate Pro is a one-time purchase, not a subscription, and adds the 3-day outlook, UV alerts, the morning briefing, household profiles, saved places, sun history with a weekly digest, and extra widgets.

Your skin type, places and sunscreen log stay on your phone, and so does the last forecast, so the ring and the shade nudge keep working without a signal.

UV values are model estimates. Burn times and the sun budget are rough personal guidance, not medical advice. When in doubt, get in the shade.

Recent changes:
v1.1.0
- Vitamin D has a season: the tile shows today's window and how far through it you are, and in winter names the day the sun gets high enough again
- The time-for-shade nudge no longer needs a signal
- A forecast that has run out shows as no data, not an old evening number
- A language change reaches the widget and reminders at once
- Today's history bar follows edits to sunscreen entries and skin type
- Data & method covers the cloud trim and the sea-level assumption