From Longman Dictionary of Contemporary Englishswelterswel‧ter /ˈsweltə $ -ər/ verb [intransitive] HOTto feel extremely hot and uncomfortable Crowds of shoppers sweltered in the summer heat.→ See Verb table
Examples from the Corpus
swelter• Monica was sweltering despite the fan revolving on her desk.• Or sweltering in taxis waiting to take the pilgrims to a restaurant.• Farm workers sweltered in the fields.• Despite sweltering in the luxury of a fire blazing full on, she received a series of credits on her budget account.• The hut was sweltering with smoke and steam and everybody scratched as vermin crept and bit under their clothes.Origin swelter (1400-1500) swelt “to die, become unconscious because of heat” ((11-20 centuries)), from Old English sweltan “to die” 