TanMeter App Store

TanMeter tool

Adjust UV Exposure Estimates for Cloud Cover

Enter current cloud cover percentage and TanMeter recalculates effective UV exposure—because thin clouds can increase UV by scattering and thick clouds still pass up to 80%.

Continue in TanMeter

Save results and unlock the full iPhone app.

Download on the App Store

How it works

  1. Check your weather app for current cloud cover percentage.
  2. Enter the cloud cover and base UV index in TanMeter.
  3. Review the adjusted effective UV level and updated burn risk.
  4. See whether SPF and safe time recommendations change.
  5. Save the adjusted reading to your TanMeter session log.

FAQ

Can clouds ever increase UV levels?

Yes. Broken cloud cover can scatter and focus UV rays, creating "cloud enhancement" spikes up to 25% above clear-sky UV.

Should I skip sunscreen on overcast days?

No. Up to 80% of UV penetrates light overcast. TanMeter always recommends SPF when the adjusted UV exceeds 3.

Does TanMeter pull cloud data automatically?

The TanMeter app auto-fetches cloud cover from weather APIs. This web tool accepts manual input for quick estimates.