From dry suit article

If water and air temps combined are less than 120° F, a wetsuit or dry suit should be worn. If water temps and/or air temps get below 50 degrees a dry suit is highly recommended.

I find the above horrible dangerous advice! Only thing that matters is really the water temps.


…and the route, the sea state/water classification, the wind, your skill, your buddies’ skills, your boat, your body type, your health…

No number can give the “right” answer.


If I’m considering strictly water temp, I go to a drysuit when the temps drop below 60°. Of course, as Acadia said, other factors are important as well. But; going just on water temp, dropping below 60° is my go to.

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60° is my limit also. Even 65° if I access I’m not going close to shore and or it’s rough.

Same here - 60F water temp is my absolute cutoff for wearing a drysuit, but I will wear it in other situations depending on the conditions, where I’m paddling etc. I am not very cold tolerant and don’t like wetsuits so will often just wear the drysuit to be on the safe side.


It would be good if we could give feedback to the author (Adrian Messner). It seems like a good overview of dry suits and it clearly serves the commercial interests of, but the introductory comments around cold water safety guidelines are misleading and just plain wrong. He could just omit the numbers.

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Contrarian here. Perhaps we shouldn’t throw out the good in order to get the perfect.

The author did not develop the 120 degree rule of thumb. That has been around for many years. It has been published in many books and magazines. It was given as a standard rule of thumb way back when I took my first sea kayaking class 20 years ago.

And I agree it isn’t perfect, but I actually think it is good for who it targets. Probably 90+% of the temperature conditions out there it is a valid guideline. And has the benefit of being simple, yet still getting people think about what to wear based on conditions. Likely has saved lived over the course of its use.

If your writing an article using info you’re endorsing it. Could have said like you did it’s a very rough rule of thumb.

From the section titled “Cold Water Myths.” Cold Water Safety

“Air + Water Temperature “Rules”

A Dangerously Misleading Message
These formulas advise you to add air temperature + water temperature to determine whether you should wear thermal protection. In other words, they say that if the air temperature is high enough, you can safely paddle on cold water without the protection of a wetsuit or drysuit. There is absolutely no scientific evidence to support these formulas and they’re dangerously misleading.

Common Example

A common example says that if the combined air and water temperatures is above 120 degrees Fahrenheit, you don’t need to wear any thermal protection.

Do The Math

Using this formula, a person could mistakenly conclude that if the air temperature was 75F (24C) and the water temperature was 53F (11.6C), no protection would be needed because the total is above 120. That’s dangerously misleading because without thermal protection, immersion in 53F (11.6C) water is immediately life-threatening.”

While I disagree with his approach to a subject or two, I can’t find anything to argue against in the website, which I’ve read in its entirety a couple times. My first thought which I’ve experienced was shortly after ice out in the ADK there can easily be water temps in the low 40’s and air temps in the mid to upper 70’s. I’ve seen similar on the Chesapeake and Penobscot Bay. Maybe there is someplace where the “120 rule” actually works but don’t think common or reliable enough that it should be advocated.


The “120 degree rule”, formerly the “100 degree” rule. Was long pushed by ACA (American Canoe Association) This rule has absolutely no scientific basis. Unfortunately, the ACA has long been considered the authoritative source for canoe and kayak safety and many other agencies, instructors and outfitters adopted this rule as well, including the USCG. The ACA, after many years of ignoring calls to drop this “rule” has finally started to quietly scrub this rule from their website and instructional materials. Of course getting the USCG and other government agencies to change their safety brochures and websites is like trying to turn an oil tanker, as is the case with many other sites where this rule can still be found. Some have never questioned it or or are still unaware of the change. That goes for some authors currently writing articles. I recently challenged an Annapolis based magazine article that mentioned the 120 degree rule, and the magazine told me the author declined to edit the article because the USCG was his source. The magazine editors, to their credit, added a note to the end of the article paraphrasing my views and that of our Club.

The ACA, being headquartered in Fredericksburg, VA near the Chesapeake Bay should have known better. The Chesapeake Bay is the largest estuary in the United States consisting of 4,479 mi² or water surface, 1,684 miles of shoreline, but averages only 21’ deep. As such, it cools very quickly, averaging some of the coldest winter water temperatures for a large body of water in the country. In the Spring, it is not at all uncommon to have water temperatures in the 40s and air temperatures in the 80s. The 120 degree rule would have you believe that it is perfectly safe to go out on big open water in shorts and a t-shirt with water temperatures well below 60. Unfortunately many do, and subsequently there are cold water related deaths every year, often combined with not wearing a PFD. Air temperature is largely irrelevant once you are in the water. Always dress for the water temperature and possible immersion.

Over the years I’ve made a few attempts to find the source for the 100 or 120 degree rule, with no success. If anyone knows, I would be interested to hear about it.


The article recommends the six most expensive drysuits in the world to all paddlers that paddle in air or water temps below 50 or 120 total. Many paddlers don’t need long term immersion protection but everyone can die from the gasp reflex which is most risky above 50F water temp. The 120 rule weights air and water temp equally which is silly at face value and credible sources are trying to re-educate the public. Around here they issue warnings to boaters in the middle of summer to not dive into Lake Michigan when periodic temperature inversions give surface water temps below 60 and people can drown from the gasp reflex with air temps above 80 (and air + water temp around 140).

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Water below 55°F I always have my kokatat balaclava on if I access much risk. Even then I stuff it in my PFD.

People are always down on the water/air combined temperature metric, and I agree that it is problematic. Having said that, I found data on water temperature for a nearby river (Quinapoxet in Holden MA)

quin tmps

And air temperature in nearby Worcester, MA (average low and high)

If you put the two together you come out with this - yellow need cold water protection, green you don’t).


It actually correlates exactly with what I do. I wear a drysuit from November through April. May and October are the shoulder months - might wear a wetsuit, might wear a drysuit, but usually wear something. June through September it is shorts and a tee shirt. So it actually does work as a guide if you use the average temperature for the month.

The obvious problem is (for instance) the rare day in April when the air temp hits 90. The water temp is around 45, so the combined is 125. Obviously no one should be in 45 degree water without cold water gear. It doesn’t work reliably if you try to use daily air temps.

Also, most people have no idea what the water temperature actually is. The water warms up slowly in the spring, and cools down slowly in the fall. Also, rivers are generally colder in the winter, and warmer in summer than the ocean. (Dam release rivers are sometimes an exception to the rule.)

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People have no idea how far away shore is till they’re up to their neck in water.

By the time fall comes most amateur’s have had enough and the water is still 60°F.

Spring everyone who didn’t paddle all winter is chomping at the paddle to get out. Long Island NY waters are the coldest March 1st. So when April hits and a nice day appears they launch. They have a million excuses to make it right in there mind. If I say you shouldn’t really be out to June 15th + they think I’m nuts.


You are absolutely right - this is Naragansett Bay at the Narragensett Town Beach (a popular surfing spot, and probably a little warmer than the open ocean)


Water doesn’t hit 60 degrees until June, and doesn’t drop below 60 degrees until October. It is coldest end of Feb/early March

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I had to look up “gasp reflex” and found this:

Good to know!!


60F water and 80 Degree air will net you heat exhaustion so your guidelines aren’t quite correct either.

No I layer less with zero problems.

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Then we have different cadence in paddling. When I’m doing sprints with my surfski in winter (just got back from one now) - I’m wearing the absolute base marino layer and nothing else. Outside temp is 48, and I’m still soaked when I’m done.

My fast cruise cadence is 70 swinging Celtic 750. Jyak counted it in a video I posted :joy: maybe less if loafing. I move very well in my hulls. Especially for an old buzzard! Yes at 70 for cadence I’d sweat at 80°.