Point of meteorology and atmospheric science at Penn State.

This is weather world.

Good evening and welcome to the world.

Today is Friday, September 18th, 2026.

I'm Rob Lydick, joined by Carl Schneider with the forecast this evening.

Carl the big story today.

Some relief finally from the humidity out there.

But I think as we'll hear on tonight's show, enjoy this weekend while you can.

Yeah.

Rob it's temporary.

Tonight and tomorrow are going to be very comfortable and dry across the state.

But then things change on Sunday in a big way.

Okay, we'll get those details on the weekend forecast from Carl in just a moment.

Also coming up on tonight's show, it's our Friday forecast frenzy.

So I'll take us through next week, which features some misty, drizzly weather and the extended forecast.

And Giannis will take us two weeks out in week two trends.

But first here's Carl and thanks very much, Rob.

The story for the immediate short range is comfort.

So tonight tomorrow going to be very comfortable and dry days.

Then things change by week time we go into Sunday, more rain chances and increasing humidity once again.

But we'll start with the four camera view, which shows very comfortable afternoon mix of clouds and sun temperatures, largely in the 70s.

So very nice evening in store for us and we can see on the temperature map anywhere from the upper 60s in northern Pennsylvania, kind of a fall like feel, but still hanging on to more of a summer like feel in the southeast.

That's going to change though, as most of us are going to be at more fall like digits throughout the weekend.

We'll have to contend with some rain, though, on Sunday.

But the big story here in the near term forecast is the dew point forecast, dew points falling into the 50s as a cold front has passed through there in northern Pennsylvania, taking a bit longer for the lower humidity to reach southern areas.

But I think it will, at least temporarily tonight and through the day tomorrow before dew points surge upward once again on Sunday.

A few spotty showers today.

It took a while for the low clouds to finally break up across central and northern Pennsylvania, but that has been in progress, and I think most of those are going to break up here in the evening hours across the south.

But just as quickly as those move out, we'll have high clouds streaming in ahead of our next system.

That's going to bring rain in here for Sunday.

But the main impact with that here in the near term is just going to be those increasing high cloud cover.

With this system, we can see a little bit better on the larger scale view.

As you see the stratiform precipitation spreading from Minnesota into Wisconsin.

That's the system that's going to affect us here late tomorrow night and through Sunday.

In the near term, though, high pressure is going to be dominating the picture.

So we won't have any rain to talk about.

It's just sort of a cloud cover forecast.

And the temperature map shows the rain cooled air across the northern Midwest.

The heat is going to stay across the southeast.

We'll just be tapping into some higher dew points.

As you can see, the dew points are surging up into the 50s and 60s, close to 70.

So as that rain moves in on Sunday, we'll have the higher dew points.

But in the near term, we'll be enjoying more comfortable conditions.

So the evening surface map shows that high pressure in control to the north.

That's the dominant feature here for the immediate term as we go through the overnight hours not much wind, the lower dew points, cooler air filtering into Pennsylvania.

But we'll see that high cloud cover streaming in late in the night.

And I think tomorrow will be one of those days where it's more clouds than sun, especially the farther west you go.

But everyone will remain dry through the daytime hours tomorrow.

We'll just have to worry about a few showers entering the picture in western Pennsylvania late in the day, but the rainfall is going to be more of the story overnight, Saturday night and into Sunday is that will spread eastward through the overnight hours.

It's going to be a steady soaking rain, looking at totals over an inch.

And much of the Commonwealth, especially areas along into the north of Interstate 80, where I think the rain will be steadier in nature through the much of the day on Sunday to the south, more of a scattered nature, and we could have a few thunderstorms which could produce higher totals.

The rain temporarily clearing out, though by Sunday evening, especially in western areas.

And then we'll have to watch this boundary lingering to the south and Rob's extended forecast, which could cause some problems heading into next week.

So tonight, considerably cooler than it was last night, you'll see low temperatures statewide falling into the 50s thanks to those falling dew points and at least temporarily clearing skies.

We'll watch the clouds move in late in western Pennsylvania, though, and that's a sign of things to come heading into tomorrow, because clouds will increase from west to east throughout the day, it will become relatively overcast by, I'd say, midday in central and western Pennsylvania.

But notice the clouds will limit the high temperatures only from the upper 60s to low to mid 70s southeast, but very comfortable feel as well as dew points remain low.

That will change though, heading through Saturday night into Sunday.

Showers will arrive late in the day Saturday evening, and that will spread from west to east overnight Saturday night and into Sunday.

I think it's more of a steady rain story along into the north of I 80, with some embedded rumbles of thunder.

Areas across southern Pennsylvania could stay dry into the afternoon, but then we'll have to watch for some thunderstorms along the approaching cold front.

We're back with the extended forecast up next.

Tonight's edition of the extended forecast will take us Monday through Friday of the week ahead.

I think temperatures will be below average throughout the Commonwealth with not much in terms of sunshine and an increased chance of rain just about every day as we look at the week ahead.

So prepare for a dreary stretch here in Pennsylvania.

Let's begin with a look at the last 48 hours on the water vapor satellite imagery.

We've had this area of high pressure.

You can kind of see the clockwise rotation of that with the northern periphery, seeing some rounds of showers and storms skirting by, this pattern begins to break down a bit more.

I think the area of high pressure will be particularly situated off to our north and east, as we go through much of the week ahead, we'll be kind of caught in the crosshairs.

In fact, an area of low pressure at the surface with kind of a boundary stalls out, and I think we'll see round after round of some showers becoming more widespread as we go into Tuesday and Wednesday of next week.

And I think we'll see our temperatures below average because of the cloud and shower coverage.

It won't be until maybe we get to Thursday and Friday where things begin to change.

This piece of energy here skirts off the coast, and we actually could see some widespread rain impacting northern New England going into Thursday and Friday.

We start to see some improvement, I think, as that pulls off, and most models are agreeing that that would be the case going into Friday of next week.

But all in all looks to be unsettled for most of the week ahead.

Here's a look at our precipitation tracker.

Sticking with NOAA's GFS model, if we see shower chances on Monday, I think it will be primarily south of I 80.

Doesn't mean that you won't see any rain to the north, but that's the best chance for seeing a soaking rain or some short periods of showers passing through, especially going into the second half of Monday.

Maybe a bit more widespread going into Monday night, Tuesday and Wednesday.

I think we could see rainy periods at any point in the day, and some models suggesting that some of that rain could be locally heavy as it moves through.

As we get into Thursday, there are some signs that that area of low pressure begins to exit offshore, begins to eventually bring some rain to New England.

And we see some wraparound showers.

I think the coverage begins to become a bit more diminished, especially by the time we get to Friday, where maybe just an isolated chance lingers, especially in eastern Pennsylvania.

By the way, as we go through next week, some signs, even some cold air damming, actually even setting up over the Appalachians, unusual for this time of September, especially given the heat and humidity that we've seen this week.

Here's a look at the extended forecast for next week.

So mostly cloudy on Monday.

Upper 50s to low 70s.

Just a bit below average for daytime highs to begin the week with rounds of showers, especially south of I 80.

But the best chance for more widespread rain occurs Tuesday and into Wednesday.

Some of that rain could be locally heavy.

It will be generally overcast through the mid week.

Times of fog and drizzle out there as well.

You'll need the jackets I think at times as we go into next week.

Highs may only be in the mid 50s to mid 60s, so dig out those hoodies.

Not much improvement on Thursday.

Some scattered rain chances continue and I think rain does become a bit more isolated on Friday.

Some breaks of sunshine.

Temperatures mainly in the 60s to near 70.

That's still below average by the way for this time of year.

Any rain chances, mainly in eastern Pennsylvania.

To wrap up the workweek, John will take us out into October in Week two.

Trends.

Up next.

Week.

Two trends is our opportunity always on Fridays to look beyond the extended forecast into the period 8 to 14 days from now, which means it will start next Saturday and end two weeks from today.

We can't provide details during that period, but we can try to give you our sense of trends.

Will temperatures be above or below average?

And what about any significant precipitation events?

I think one change after we get through next week.

At the beginning of the week two period, I do think we'll see a multi-day stretch of weather with no precipitation.

If we're going to try to assess whether temperatures will be above or below average, it helps to know what the rapidly changing averages are this time of year.

This will be right in the middle of that 8 to 14 day period.

These numbers are down three degrees across the board from last week.

At this time.

That's what happens when you're losing daylight at the rate of about 19 minutes per week.

So keep these numbers in mind as we assess the risk of temperatures being above or below average.

We use an ensemble of forecasts to do this.

These lines represent pressure up around 200 zero feet.

The wind tends to follow these lines from west to east, where they dip to the south.

We call these troughs.

These often bring cooler than average weather and rainier weather to their east, where the lines bulge.

To the north we call these ridges.

They're often associated with relatively warm air aloft and relatively dry weather.

As we go through time, the individual colored lines will begin to separate.

That's a sign that the different model solutions are.

Not agreeing in the solutions.

And we look at how the red lines are spread across the eastern United States.

Already, some uncertainty being introduced in the middle of this week.

And by the time we get to the beginning of my forecast problem, which is next Saturday, notice how it looks like Christmas in Pennsylvania.

Red lines are intersecting green lines.

There's a lot of uncertainty here.

And by the way, the white line is trying to average out in this case, the red lines.

And that large uncertainty continues into next Sunday.

Now, what I do like about this pattern, if you want it to dry out, however, is that the main axis of the dip, the so-called trough, is to our east, and the ridge or the bulge in the lines is to our west.

And in between those two is often a place where air tends to sink.

Uh.

Nights are cool and precipitation is relatively sparse, and I think we'll be in that sweet spot at the beginning of the week two period.

Same on Tuesday.

This ridge comes right overhead.

I think another storm may follow that, but the general pattern by the time we get to the end of week two is rather zonal.

And actually looks rather seasonal in terms of temperatures.

And that's what you'll see on the week two checkerboard.

I think there might be a cool day next weekend, but that's largely because temperatures will be on the cool side at night and maybe one mild day early in week two.

But a most confident about a dry period that could begin next Saturday and extend through Tuesday of week two, and then a period of showers.

So a multi-day dry stretch to start the week two period, and then possibly some midweek wetness.

It will feel like fall most of the time, which means highs in the 60s and the 70s.

That's it for week two trends.

Back in a moment with more.

Dry and very comfortable.

Evening is in store for the Commonwealth.

Probably.

Good evening for a backyard fire.

I'm thinking about that here myself this evening.

Falling dew points will allow lows to fall into the 50s statewide, mostly clear for most of the night.

Then clouds increase in the west ahead of the approaching cloud cover for tomorrow, cloud cover increasing from west to east throughout the day, eventually becoming overcast, but all of us staying dry.

So this is going to be the day if you got to mow the grass.

I would do this on Saturday because Sunday is going to not be the same.

As showers arrive in western Pennsylvania late and then spread through the state overnight, it will be steady rain along and north of I-80 through much of the day on Sunday.

Some folks in the southeast could stay dry until the afternoon, where I expect a few thunderstorms to develop.

Along the cold front is that passes through highs both days, anywhere from the upper 60s to mid 70s.

So as I said, Rob, looking like tomorrow is going to be the better of the two days for outdoor activities.

Probably not much going on on Sunday.

Yeah.

One of those things where I like to your recommendation to get the mowing done, because I still have to do that.

And before we get into that rainy stretch next week, you want to tend to the backyard, maybe even do some sucking up of the leaves.

I've seen quite a few of them falling off my tree, too.

Yeah, absolutely.

All right.

Well, thanks so much for your forecast tonight, Carl, and thank you for tuning in.

We'll see you back here on Monday with hashtag headlines.

Have a great weekend.