Ever heard the saying, “it’s not the heat that’ll get ya. It’s the humidity”? There’s a reason that’s a saying.
Rochester’s dew point temperature (the temperature at which air becomes fully saturated) has been in the upper 70s this morning. That’s REALLY high in this part of the world. In fact, it’s one of the highest readings anywhere in the United States so far today. Yes, that means it’s higher here than places like Florida, Alabama & Louisiana. And by a good margin, to boot.
Days like today stress the importance of focusing not only on the temperature, but the impact humidity has on all of us. We likely won’t be setting any record highs during this heat wave. Part of the reason for that is because of how incredibly high our dew points are. You know how Lake Ontario is often much cooler than inland areas this time of year? Air heats up more efficiently than water. Same premise here. Dry air heats up faster than air with a whole bunch of moisture in it. Part of the reason we won’t be setting record highs is because of all that moisture in the air. If humidity values weren’t so high, we probably would be setting records.
Superficially, that can make it seem like a stretch of highs in the lower and middle 90s isn’t a big deal. But when you factor in those very high dew points, it becomes a much bigger deal. Heat index values are already pushing 105°. You step outside right now and it just feels different than a “typical” 90° day. That’s the effect of all that moisture. Humans cool by sweating. Sweat evaporates, which cools us off. Sweat doesn’t evaporate nearly as effectively when it’s humid like this because the air is already full of moisture. So, we keep sweating and sweating, overheating and overheating. This is why our heat index is largely driving the Extreme Heat Warnings across the area. Focus on just the air temperature, you’re only getting part of the story…