After a very spring-like start to the week, the Tri-State Area will be under extreme heat by Thursday. Temperatures will break 90 degrees starting Thursday, but the difference between the heat this week and what we’ve faced during earlier hot spells is that humidity levels are going to spike, too. The best indicator of just how muggy it’s going to feel is to look at dew points. The higher the dew point, the higher the humidity. When we approach or exceed a dew point of 70, the humidity is stifling.