Paris Alston: This is GBH’s Morning Edition. Well, it’s not quite another heat wave, but we are getting some high temperatures this week, up near 90 this afternoon, and dew points will be rising later today. To break down the forecast and answer some plant- and weather- related questions, we’re joined by our meteorologist, Dave Epstein. Good morning Dave.

Dave Epstein: Good morning. Good to be here.

Alston: So let’s get into this forecast. What can we expect for this week?

Epstein: Yeah. So it looks great if you’re on vacation. You know, the kids are out of school at this point, so I do know that some folks like to take their vacations a little bit early. It looks like a fantastic week. Today is an absolutely stunning day. We’re up between 85 and 90 this afternoon. Humidity levels are going to be low all day long, so you’re not going to have to worry about that sticky feeling in the air at all. Overnight tonight will still be mild. It’ll be a great evening to get outside, do some barbecuing, want to play around to golf? Maybe tee time at 4 p.m., get you off before sunset. Temperatures down near 70. On Wednesday, mostly sunny, a little more humid. It’s not going to be oppressive, but we’ll definitely notice that uptick in the humidity. Temperatures up near 90 once again, mostly sunny. And then there’ll be a front moving through with some showers and storms here Wednesday night into early Thursday, then partly sunny and drying out again. And it looks like another stunning day on Friday. A little cooler temperature right around 80 degrees with low humidity. A great sleeping night I think Thursday night, Friday night, and even maybe Saturday. But definitely Thursday and Friday night are going to be fantastic. Windows open kind of nights.

Alston: Ooh, something to look forward to there. Nice summer night there. So, Dave, last week when we did have that heat wave, one thing you mentioned was the fact that the humidity can make it feel even hotter. Explain how that works.

Epstein: Yeah. So basically it’s the dew points go up, the amount of moisture in the air increases in the way that humans and others, you know, depending on the animal, feel cooler — but let’s stick with humans — is that we sweat. And so when you sweat, that moisture on your body evaporates. And that evaporative process is a cooling one. So evaporation actually leads to cooling. If it’s really humid, the process is really slowed down almost to a crawl. And now you don’t feel cooler. So you tend to just sweat and the water is not evaporating and the cooling process isn’t working. So the good news is this afternoon it is going to be near 90. But I do think that the cooling process will be working really nicely so it won’t feel quite as hot. The sun is very strong. We’re at our peak sun this time of the year, so you definitely want the sunscreen on. You can get burned in as little as 15 or 20 minutes out there in full sun.

Alston: Oh, yeah. Good reminder there. So let’s switch gears here a bit and answer some listener questions. First up we have one from Roy in Wellesley, who’s saying we just experienced a sudden outbreak of houseflies. We know this is something that happens every summer, right? But he says this is coming from the basement, perhaps wasn’t able to find what they might be feeding on. Is it possible that they’re somehow related to the sudden heat spell? I’ve heard that cluster flies sometimes arise when there’s an abrupt, warm spell in the winter.

Epstein: Yeah, so I’m not an entomologist, so I want to stick to my lane, as they say. But, you know, there’s probably something in the basement that they fed on, that they pupated. So the flies lay their eggs, the eggs hatch, you get a larvae, the larvae pupate, and then the flies hatch. The heat could have sped up that process a little bit. And certainly the warm weather, they do hatch in that. But in terms of what’s going on there, call your expert.

Alston: Yes. That does have me curious about fruit flies, Dave. I don’t know how much you know about that, but obviously they could be really prevalent in the summer. Do you have any tips for keeping them away?

Epstein: Yeah. I mean, there’s all sorts of little tricks. What I do is I actually take a piece of Saran wrap and put it a little bit of red wine and pokes very small holes in that, and I put a little drop of dish soap in the red wine, and then the flies tend to go in there and they jump into the red wine, and then that capture some of them. That’s my little trick. Go on the internet. There’s tons of them out there.

Alston: It sounds like you give them at least a nice little nightcap. As they’re going down.

Epstein: Yeah, exactly. They die drunk. So, you know.

Alston: Okay, we got another question here from Ed in Newton, who says: My hydrangeas get about a half day of full sun and droop every sunny afternoon. So it sounds like today might be a rough one for the hydrangeas for Ed. What is the best way to deal with this?

Epstein: Yeah, I mean, they’re pretty much, that’s just what the plant does. I’ve got, I’m looking outside as I’m speaking with you. I’ve got some. They’re absolutely stunning this year. And I’ve got some beautiful ones and, yeah, no matter how much you water them, that heat, they’re just basically protecting themselves. So the drooping is so that they’re losing less water and then they’ll just come back. You can make sure that you keep them evenly moist with the soil. It may prevent the drooping a little bit. But a day like today with the sun, the hydrangeas are going to droop. It’s what they do.

Alston: Well, that is meteorologist Dave Epstein chatting all things weather and plants. If you ever have a question for him, text it to 617-300-2008. Dave, thank you so much.

Epstein: Thanks. Good to be here.

Alston: You are listening to GBH news.

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.

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

My hydrangeas get about half a day of full sun and ‘droop’ every sunny afternoon. How best to deal with this? —Ed Dailey, Newton

This question calls for a bit of understanding about how hydrangeas protect themselves from heat, Epstein said.

“That’s just what the plant does,” he said. “I’ve got some beautiful ones and, yeah, no matter how much you water them, in that heat, they’re just basically protecting themselves.”

You can try to make sure you keep the soil around them evenly moist, he said, but you may still see some drooping on very hot days. So long as they rebound when the heat subsides, it’s not a cause for concern.

We just experienced a sudden outbreak of house flies, perhaps coming from the basement, but I wasn’t able to find what they might be feeding on. Is it possible that they’re somehow related to the sudden heat spell? —Roy in Wellesley

It’s hard to say for sure without more information, Epstein said, but the heat can accelerate flies’ pupation process.

“There’s probably something in the basement that they fed on,” Epstein said. “The flies lay their eggs, the eggs hatch, you get a larvae, the larvae pupate, and then the flies hatch. The heat could have sped up that process a little bit.”

Along with larger house flies, people may see more tiny fruit flies around their homes in the heat, Epstein said. To deal with them he makes a DIY fly trap by putting a bit of red wine into a cup, adding a drop of dish soap, and covering the cup with plastic wrap, in which he pokes tiny holes.

But for a more definitive answer, he said, call your local bug expert.

“I’m not an entomologist, so I want to stick to my lane,” he said.