From Longman Dictionary of Contemporary Englishprickly heatˌprickly ˈheat noun [uncountable] MIa skin condition in which you get uncomfortable red spots on your skin. Prickly heat is caused by too much strong sun on your skin.
Examples from the Corpus
prickly heat• A prickly heat pressed against his face.• A prickly heat pressed against his face; the teakettle made hissing sounds in the night.• Q I get prickly heat every time I go in the sun.• It is not prickly heat, it is more likely to be Polymorphic Light Eruption, an allergy to the sunshine.• After all, for most of us, a holiday just isn't a holiday without a bout of prickly heat.• Covered in a kind of prickly heat. 