Thinner blood, however, "is absolutely a myth," said Dr. Bruce Lenes, medical director of Community Blood Centers of South Florida, noting that blood thickness isn't influenced by temperature. ... While warmer temperatures don't thin out blood, living at high altitude does, Lenes said.

Does temperature affect blood thickness?

Changes in perception of heat and cold are highly individual, but “the thickness or viscosity of our blood has nothing to do with how we experience the temperature,” said Holly S. Andersen, director of education and outreach for the Perelman Heart Institute at NewYork-Presbyterian/Weill Cornell Medical Center.

Does your blood get thinner in a hot weather climate?

Answer. No, the concept of developing "thinner blood " by moving from a colder Northern climate to a warmer Southern climate is only a myth. People may often feel colder at times after moving to the South from the North, but this is not the result of their blood getting thinner.