in/under the hot sun

in/under the hot sun
Either one is acceptable, but the style of the sentence is awkward. Try using some other adjective for the sun - the phrases "very hot" and "hot sun" are too close together.

The word you want is "in", though, not "under"... for example:

He got very hot sitting in the sun.

Many thanks.

"There's nothing new under the sun"

http://www.phrases.org.uk/bulletin_board/17/messages/54.html

http://www.quotationsbook.com/search/quotes/?term=under+the+hot+sun

It is an old story, this life of ours. There is nothing new under our sun. Nothing new, that is, for us, as we now feel and think - Josiah Royce

http://www.brainyquote.com/words/su/sun226129.html

"Pain and foolishness lead to great bliss and complete knowledge, for Eternal Wisdom created nothing under the sun in vain." Kahlil Gibran

http://thinkexist.com/search/searchquotation.asp?search=under%20the%20sun&page=2

Mad dogs and Englishmen go out in the midday sun.