Most water spots are mineral deposits (from hard water) left as rinse water evaporates. Hot panels and direct sun speed evaporation, increasing the chance of visible spotting.

Why weather matters

  • Heat + sun: flash drying, faster deposits.
  • Wind: can dry quickly (good) but also dries drips before you catch them (bad).
  • Humidity: slows evaporation; reduces flash spots but can leave more streaky drips.

How to reduce spots

  • Work in shade where possible.
  • Rinse thoroughly and dry immediately.
  • If you have very hard water, consider a final rinse with filtered water (or dry faster and more thoroughly).