Special Weather Discussion

Latest Weather Discussion by Kyle Elliott

* Nor'Easter to spoil weekend plans with wind, rain *

12:30 p.m. Friday, September 25, 2026, Update:

The last full week of September will end on a mostly sunny, dry, breezy and pleasant note this afternoon with high temperatures in the low-to-mid 70s and dewpoints around 50°F. A sprawling high pressure system over southeastern Canada and the Great Lakes region will promote the beautiful conditions. A strong pressure gradient, or difference in pressure, between a developing storm system several hundred miles off the mid-Atlantic coastline and the area of high pressure will cause northerly winds to be sustained at 10-20 mph with gusts up to 30 mph (see below). Needless to say, it will be a nice day to enjoy the Great Outdoors after work or school.

Unfortunately, the beautiful weather will not last through the upcoming weekend. The storm system will rapidly intensify over the next 24-36 hours and then hook back west toward or into New Jersey and the Delmarva coastline over the weekend. There is still some uncertainty regarding the maximum strength of the storm system, its track, and how far west it gets. These three factors will determine the distribution of rainfall amounts, maximum wind gusts, and duration of showers/rain both Saturday and Sunday. A stronger system with a more westward track would result in higher rainfall amounts and wind gusts across northern MD and southeastern PA, while a weaker system would mean lower amounts, lighter winds, and less hours of wet weather over the weekend. After a mainly clear and comfortable Friday night with lows in the mid 50s, skies will turn mostly cloudy Saturday morning with a few passing showers to follow during the midday and afternoon hours. Areas west of Route 11/I-83 and perhaps even the Susquehanna River may not receive any rain until later Saturday night, but several bands of showers could impact far southeastern PA during the daylight hours. Following a brief lull in the activity Saturday evening, steadier rain will overspread the region from east-to-west later Saturday night into Sunday morning and then continue into the evening hours (see below). The system should weaken dramatically from Sunday night into Monday and slowly pull back into the open waters of the western Atlantic. As a result, rain should gradually taper off Sunday night with no more than a lingering shower on Monday. Due to the clouds and wet weather, high temperatures will be around 5°F below average on Saturday (mid 60s to low 70s from west-to-east) and 10-15°F below normal on Sunday (upper 50s to low 60s). 

At this point, rainfall amounts and their distribution over the weekend are rather uncertain. However, totals will almost certainly increase from west-to-east across the region, and areas near Philadelphia could receive as much as 1-2" from the system. On the flip side of the coin, areas west of Route 11/I-83 may receive less than 0.25" of rain. A subtle, 50-mile shift in the system's track, one way or the other, will have big impacts on rainfall totals, much like during a winter storm. Regardless, expect wet roadways and standing water in spots on the way to-and-from Sunday morning church services, and keep an umbrella handy this weekend. You shouldn't have to cancel outdoor plans on Saturday, but Sunday may easily turn into a complete washout and perfect day to watch NFL football games on TV. I do not anticipate any flooding issues due to the prolonged nature of the event and lack of heavy rain, but northerly wind gusts of 35-40 mph will make it feel truly miserable outside on Sunday. The good news? By Monday, the system will have weakened so much that wind speeds should be sustained at 10-15 mph or less, and skies may partially clear by the afternoon hours with high temperatures back around 70°F. Further improvements in the weather are then a virtual guarantee during the middle of next week. An area of high pressure will build into the central Appalachians and mid-Atlantic States from Tuesday into Wednesday and promote a continued moderating trend in temperatures. In addition, skies should turn partly sunny by Tuesday and mostly sunny on Wednesday with afternoon high temperatures in the mid 70s and upper 70s to perhaps low 80s, respectively. Overnights should be comfortable with lows in the 50s both Monday and Tuesday nights. I'll wrap things up there for now, so check back early next week for an update! -- Elliott 

2:00 p.m. Tuesday, September 22, 2026:

In the wake of Sunday night's cold frontal passage, northeasterly winds ushered much cooler and drier air into the Lower Susquehanna Valley on Monday. Under mostly cloudy skies, temperatures only peaked in the mid 60s to low 70s from west-to-east across the region. A few showers dampened northern MD and south-central PA Monday afternoon and evening, but steadier rain held off until the overnight hours. Strengthening, northeasterly flow is continuing to draw moisture from the Atlantic up against the eastern slopes of the Appalachians and also interacting with a disturbance moving eastward through the mid-Atlantic States. As a result, intermittent light rain and drizzle will persist for a few more hours before gradually tapering off and ending later this afternoon and evening. Most areas will receive an additional 0.05-0.15" of rain with storm total rainfall of 0.25-0.50" near Philadelphia to 0.75-1.25" across most of central PA. Overall, the rain is still largely beneficial, and flooding hasn't been an issue due to the absence of heavy downpours and prolonged duration of the event. Keep an umbrella handy through the PM commute, and expect delays and areas of slow travel on the wet roadways. Drive within the speed limit and increase following distance to reduce the risk of hydroplaning or an accident. Temperatures will remain nearly steady in the upper 50s to low 60s.. about 15°F below average.. through the early-evening hours and then bottom out in the low 50s tonight. Autumn officially begins at 8:04 PM EDT, and it certainly feels the part outside this afternoon (see below). It's jacket or "sweatshirt weather" at its finest!

A sprawling high pressure system over southeastern Canada will gradually build farther south and west through the end of the week and suppress the rain into the central Appalachians and southern mid-Atlantic States on Wednesday, Carolinas on Thursday, and into the western Atlantic Friday. As this occurs, drier air from Canada and northern New England will be drawn southward, and skies should at least partially clear on Wednesday north of the Mason-Dixon Line. Clouds should continue to erode from north-to-south from Wednesday night into Thursday morning, and skies could actually turn out mostly sunny late this week (see below). Dewpoints will drop from the 50s this afternoon into the mid-to-upper 40s from Wednesday-Friday, and the 10-20 mph breeze will persist through week's end. In terms of the wind direction, it should turn northerly by Thursday night or Friday and then remain north-to-northwesterly over the weekend. High temperatures will likely be around 10°F below normal (mid-to-upper 60s) both Wednesday and Thursday but moderate back into the low 70s from Friday-Sunday.

A tight pressure gradient, or difference in pressure, between the aforementioned high pressure system and a deepening storm system hundreds of miles off the East Coast will promote a continuation of breezy conditions over the weekend. How close the storm system tracks and/or backs westward toward the immediate coastline will determine just how high wind speeds are locally, as well as the degree or extent of cloud cover. However, odds currently favor a track farther offshore due to a lack of high-latitude blocking over Greenland and the North Atlantic. Thus, I expect a continuation of partly-to-mostly sunny and breezy, but pleasant, conditions on Saturday and Sunday with high temperatures in the low-to-mid 70s and overnight lows in the low-to-mid 50s. The moderating trend will likely continue into early next week, and high temperatures may be back around 80°F next Tuesday under mostly sunny skies with the high pressure system still in control of the weather. Needless to say, it's going to feel like fall this week, and temperatures should be ideal for sleeping with the windows open at night and enjoying the Great Outdoors after work or school. Check back Friday for an update on the offshore Nor'easter and its proximity to the coast over the weekend! -- Elliott