Outside Jewell

Dress for the Water Temperature

It’s Spring. Do you know what the water temperature is?

Portland Harbor, Maine averages: May 1-15 = 47ºF / May 16-31  = 51ºF

Every Spring, warming air entices many people to go out in small boats when the water temperature is still deadly cold. 50ºF water doesn't sound particularly cold or dangerous if you mentally compare it to 50ºF air.

Average sea water temperatures  in Portland, Maine:

  • January 34ºF
  • February 33ºF
  • March 37ºF
  • April 1-15 39ºF; April 16-30 41ºF
  • May 1-15 47ºF; May 16-31 51ºF
  • June 56ºF
  • July 61ºF
  • August 62ºF
  • September 59ºF
  • October 52ºF
  • November 47ºF
  • December 39ºF
Relative Water Temperatures
True or False?

If the combined air and water temperatures are below 120 degrees Fahrenheit, a wetsuit is a must and a drysuit is highly recommended.

False. Using this formula, a paddler could mistakenly conclude that if the air temperature was 72F (22C), no protection would be needed in 53F (12C) water – because the total is above 120. (72F + 53F = 125) That’s simply incorrect.

No one ever plans on capsizing.

Cold water doesn’t have to be freezing cold or over your head to kill you. No one ever plans on capsizing. Many people who can swim have drowned within 6-10 feet of shore due to cold shock and swimming failure.

Weather and water conditions often change quickly and dramatically. Water temperatures do not change so radically. No matter how strong, fit, determined or motivated you are, sudden immersion in cold water is a life-threatening event. What really matters when you’re in the water is whether or not you’re dressed for immersion.

Rock Landing

Rock landing in Cornwall. Photo by Liz Johnson.

Corresponding Temperatures in Farenheit:

5ºC = 41ºF

10ºC = 50ºF

15ºC = 59ºF

20ºC = 68ºF

For more information, see the website of The National Center for Cold Water Safety.

Featured photo by Joe Guglielmetti.

Posted in Water Safety.