Left birth control in glove compartment of car overnight and took it out late this morning. Will effectiveness be altered? It was 84 degrees outside

Probably OK... Most contraceptive pills ask that you do not store them in temperatures over 77 degrees. Hormones can denature at high temperatures; however, A single, short exposure to 84 degrees isn't likely to keep them from working. I wouldn't make a habit of this. Your pill should come with a package insert that gives the storage temperature recommendations. If worried get a new pill pack. Best wishes!