Jeremy Seigel: You're listening to GBH's Morning Edition on a dry and cool morning. In fact, we are entering the time of year when it's getting consistently colder and so dry that your hands might start feeling like sandpaper. If you are keeping the hand cream near, you're not alone this time of year because it is dry skin season.

Paris Alston: Oh yes. The Morning Edition team lead on a healthy layer of hand cream all together this morning.

Seigel: We got the communal cream going around. Yeah.

Alston: Yes, but we're all wondering, is there a way to beat the season and predict what day might be harsher on your skin than others? To help us answer that question, meteorologist Dave Epstein is here. Hey, Dave, Good morning.

Dave Epstein: Good morning. Good to be here.

Seigel: It's good to see you. So we all know, obviously, that winters are bad on our hands. Our lips, too. But what is the weather behind it? Why is it so bad?

Epstein: Yeah. So in winter we get Canadian and even Arctic air to move into the area. And as that does so, the dew points, the amount of moisture in the air, lowers. So that number, like I just looked at the dew point right now is 24 in Boston. A couple of days ago it was down to like, 8. And so when you get those dew points down in the single digits and even below zero — we had dew points last winter, a couple of times in the -5 to -10 degree range — there's not much moisture in the air. And so what moisture you have in your skin gets evaporated really fast. And that's why your hands and your lips and everything else dry out so much. And your furniture as well, it's not good for that.

Alston: Yeah, I guess. Is that why people keep plastic on? I don't know. Anyway, but we talked about this before, Dave, because, for instance, like looking at my phone, I see it's 62% humidity.

Epstein: Yeah.

Alston: But that dew point, it seems like what you're talking about is that dew point is what saps some of that moisture out even though it may not actually feel that way.

Epstein: Yeah. So think of it this way: The relative humidity just says how full the air is of moisture that it could have on this given day. So we're a little over half full of moisture. Well, if the dew points down at 10, what that tells us is the air can't hold much moisture. So even if you have a 90% relative humidity at a 10 degree dew point, there's so little moisture still that it doesn't matter. Whereas 50% with the dew point of, say, 70 — that's going to feel really humid. So the percent can be less, but there's actually more moisture in the air. It's like a pool. A pool can be half full and have way more water than an 8-ounce glass that's completely full.

Seigel: We're talking with meteorologist Dave Epstein about dry weather and dry air. I guess Paris has already covered some tips for keeping your sofas warm and dry.

Alston: And clean.

Seigel: Or warm and moist during this time. But, Dave, you got any tips for making sure that your skin stays okay and healthy this time? I mean, I know like moisturizer, using lotion. Is there anything else?

Epstein: Yeah. I mean, don't take hot, hot showers aren't good either. That tends to dry your skin out. So, you know, I tend to try to take cold showers actually.

Alston: In the winter?

Epstein: Yeah, I went swimming in Maine this weekend in 48 degree water. So I should say I dove and I want to overstay wet.

Alston: Talk about a polar plunge.

Epstein: Yeah. So, you know, I mean, that's one way. The heat really dries it out. Humidifiers in your house, right? If you have a humidifier, that's really helpful as well. And yeah, just the creams, continue to use creams. And also your wood furniture could use some furniture polish that has some cream in it in the winter because if your house is really dry, the wood can crack.

Alston: Oh, I love the idea of thinking of like my dresser is having a layer of skin on its own, right, in the same way we need to take care of ours.

Epstein: Yeah, there you go.

Alston: So, Dave, we got the hand cream handy. We got the furniture polish here. But are there any other precautions we should take? For instance, right now it is cloudy. We are expecting sunshine today, though. So do we still need to keep the sunscreen nearby?

Epstein: Yeah, the sunscreen stuff this time of the year, I'm a fan of not using it because when you put the sunscreen on, you don't get the benefit of the UV rays. The sun angle is so low this time of year, it's basically at its highest, it's like 8:30 or so in the morning in the middle of the summer. So it's not that kind of strength. So I think right now you can get away without the sunscreen. Obviously, if you have sun issues, skin issues, then you still want to use it if your doctor recommends it. But I don't really use it deep in the winter.

Seigel: That is GBH meteorologist Dave Epstein. Dave, thank you so much, as always.

Epstein: You're welcome. Good to be here.

Alston: You're listening to GBH's Morning Edition.

Meteorologist Dave Epstein is our go-to person for pressing weather questions on everything from winter blizzards to summer droughts. He’s also a horticulturist, meaning he’s an expert in anything that grows leaves and flowers. GBH's Morning Edition asked our audience for weather and gardening questions, and Epstein graciously answered them on the air. This transcript has been edited for clarity.

Have a gardening or weather question for meteorologist Dave Epstein? Tweet him  @GrowingWisdom, email us at  thewakeup@wgbh.org, or text 617-300-2008.

Why do we get dry skin in the winter?

There’s a meteorological reason behind heavy hand cream season, Epstein said. And to understand which days will be drier, it helps to have a sense of dew points and relative humidity.

In the winter, Boston gets colder air from Canada and even the Arctic traveling down to the area. And as the colder air comes in, dew points get lower.

The dew point is a measure of the atmospheric temperature. Below it, water condenses and dew can form. Generally speaking, the higher the dew point, the more humidity can be in the air.

Another common measure is relative humidity: A measure of how full the air is of the moisture it could have.

Relative humidity by itself can be misleading, Epstein said. On cold days, a high relative humidity doesn’t translate to much moisture in the air.

“If the dew point is down at 10, what that tells us is the air can't hold much moisture,” Epstein said. “So even if you have a 90% relative humidity at a 10 degree dew point, there's so little moisture still that it doesn't matter.”

Picture a day with a high dew point and low relative humidity as a half-full pool, and a day with a low dew point and high relative humidity as a full glass of water, he said.

“A pool can be half full and have way more water than an 8-ounce glass that's completely full,” Epstein said.

All of that to say: On less humid days, dry skin abounds.

“When you get those dew points down in the single digits and even below zero — we had dew points last winter, a couple of times in the -5 to -10 degree range — there's not much moisture in the air,” Epstein said. “And so what moisture you have in your skin gets evaporated really fast. And that's why your hands and your lips and everything else dry out so much.”

So what can the dry skin-averse do? Keep moisturizers and lip balms handy, Epstein said. Keep showers shorter and not too hot, as the heat can also contribute to dry skin.

Humidifiers can help too, he said. And when the air is dry, wood furniture can also suffer, he said.

“Your wood furniture could use some furniture polish that has some cream in it in the winter because if your house is really dry, the wood can crack,” he said.