When treating frostbite with warm-water immersion, the water should be no higher than about 39–40 °C (roughly 102 °F).

Safe water temperature

  • Medical and wilderness guidelines recommend a warm water bath of about 37–39 °C (98.6–102.2 °F) to rewarm frostbitten tissue.
  • Several clinical quick-reference guides specify an upper limit around 39–40 °C , emphasizing that hotter water risks burning already damaged skin.

Why not hotter?

  • Frostbitten tissue is numb and damaged, so a person cannot reliably feel if water is too hot, increasing the risk of scald burns.
  • Controlled “rapid rewarming” at this temperature range improves outcomes compared with slow or excessively hot rewarming, which can worsen tissue injury.

Simple takeaway

  • Aim for warm, not hot, water: about body temperature, and definitely not hotter than around 39–40 °C (≈102 °F) when treating frostbite.

Information gathered from public forums or data available on the internet and portrayed here.