in the heat of

In the most intense or active stage of some activity or condition. For example, One never knows how soldiers will behave in the heat of battle, or In the heat of the moment she accepted his proposal, or In the heat of the negotiations he forgot to call his wife. [Late 1500s]

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.