Summer-style humidity arrives this week, could hang around for good

After a cool-ish, but very pleasant start to the month of May, our heat and humidity will get dialed up several notches this week.

Temperatures will stay above average…just how warm though depends on how many clouds and showers we have around, but humidity levels will be quickly climbing and be more reminiscent of mid-summer by the end of the week.

A large area of high pressure will drift from the central United States to the southeast. This is a classic set up for what we call "opening the Gulf." It’s a term used when southerly winds pull high levels of moisture out of the very warm Gulf of Mexico. This pattern often times sends huge amounts of moisture all the way to southern Canada. This is where 90% or more of our overall atmospheric moisture comes from in the summer season. It’s the main reason why Minnesota and all areas east of us are very humid in the summer and why places to our west are much dryer.

The leading surge of moisture is likely to arrive Wednesday when a warm front lifts northward through the state. This will push dew points from the current comfy levels of the 40s and low 50s, to the far more aggressive and humid 60s for what could be a large chunk of time.

comfort level

Comfort level when it comes to dew points: 40s and 50s are comfy, 60s get humid and then 70s are just ridiculous. 

Unlike the often talked about relative humidity back in the 20th century, dew points are a very efficient and consistent way to measure humidity and comfortability in our atmosphere. The confusion with using relative humidity is that it’s relative to the temperature, therefore a 90% humidity level could feel really comfortable or really miserable because it all depends on your temperature. But with dew point, a 65-degree reading will ALWAYS feel humid, no matter the temperature. Just like a 45-degree reading will ALWAYS feel comfortable.

While it’s unlikely that this level of humidity stays for good, our comfortable days look to be on the way out as summer-time humidity begins to grab hold.