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Climate and Environment

Yes, LA, What You're Feeling Is Humidity. The Science Behind That Sticky, Gross Sensation

A gauge to measure humidity shows a dial with a red indicator measuring 65 percent
Meters that measure humidity are hitting unusually high levels in Los Angeles.
(phattaraphum
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Getty Images/iStockphoto)
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Honestly, I kind of forgot about humidity.

It’s been so damn dry all year, my often dehydrated brain has humidity amnesia. But apparently, this sticky, moist weather is pretty average for a SoCal summer.

National Weather Service meteorologist Joe Sirard said by July, the summer heat warms up the ocean enough to create more vapor in the air.

“So it does feel a little sticky out there," he said, "especially the further inland you go into the area."

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But what is it about this kind of weather that makes us really feel the humidity in the air?

Well, it's not just plain humidity percentages that meteorologists track. The dew point really captures how we experience the humidity, and in the past few muggy days, the L.A. region has had a dew point in the 60s — exactly the point where our bodies start to register the humidity around us.

Okay, so then why does feeling humidity also make the air temperature feel warmer?

That’s got to do with what’s called the wet bulb temperature. And that number relates to how the body can cool itself.

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Sirard explained that wet bulb temperature is about halfway between the air and the dew point temperatures.

“Say for example it's 80 degrees out, the dew point is 60, then the wet bulb would be around 70ish,” he said. That means when you’re sweating and a breeze blows across your skin, “it'll cool the skin down to like, 70 degrees.”

You may have seen the term wet bulb more often in the news lately. Scientists are trying to raise public awareness about the daily wet bulb temperature in an effort to save lives. That’s because high temperatures and humidity caused by climate change are raising the web bulb temperature to where even healthy people cannot regulate their body temperature and could die from heat.

As for the current wet bulb temperature in L.A., we can thank the nearby ocean. With the summer sun higher in the sky, the Pacific is warming up. Onshore winds then carry that water vapor inland.

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Some of that vapor has developed into actual rainfall. There even have been some scattered showers in the past week. In a statement that drives home the context of relativity, the National Weather Service reports that Los Angeles is having its fifth wettest July on record (aka since 1877). Which, isn’t saying much. It took just .10 inch of rain in downtown Tuesday to get us there.

There’s also the monsoon moisture that comes to our area in August to early September. And we are seeing a little of that now. “Recently we have been in kind of a monsoon flow as well, so that's also helping to keep these humidities a little bit higher,” Sirard said.

So, if like me you’re hating the humidity, it won’t really pass until the end of summer. But these high levels above 60% should break in just a few more days.

In the meantime, all of our tropical house plants purchased during pandemic lockdown are happy. Let’s focus on that.

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