Two hypothermic green sea turtles that stranded in Dennis Wednesday morning were taken for medical treatment and rewarming at the New England Aquarium Sea Turtle Hospital in Quincy, the aquarium said.

The turtles were the first live ones to wash up along the Massachusetts coast this season, which the aquarium called “a sure sign of winter in New England.’’ The Mass Audubon Wellfleet Bay Wildlife Sanctuary collected the turtles and brought them to the aquarium’s turtle hospital.

In Quincy, the reptiles will have their bodies slowly warmed over several days from their current temperatures in the 50s. They will also be treated for conditions, including pneumonia and dehydration, that they developed in recent months as ocean temperatures gradually dropped and they slowly became hypothermic, the aquarium said.

Turtles that strand along the Bay State coast are typically juveniles that visit northern Atlantic waters each summer to feed on crabs, the aquarium said. Some turtles that venture to the north side of Cape Cod for food can become trapped when fall arrives if they aren’t able to navigate out of Cape Cod Bay.

As temperatures drop, they become stunned by the cold. And once they become inert, northwesterly or northerly winds of 10 miles per hour or more can push the floating animals onto land.

While Nov. 15 is a late start to the turtle stranding season, the aquarium said, the delay is likely due to warmer-than-average weather this fall that kept local Atlantic waters above normal. This past weekend’s cold snap sent ocean temperatures off Massachusetts into the low 50s, around “the critical threshold at which strandings begin,’’ the aquarium said.

The two turtles that washed up in Dennis are likely the first of many. Depending on the weather, hundreds of sea turtles can strand on the Cape through December. Since 2011, an average of more than 300 of the stranded turtles have been treated during the winter.

Ben Thompson can be reached at ben.thompson@globe.com. Follow him on Twitter @Globe_Thompson