Special Weather Discussion

Latest Weather Discussion by Kyle Elliott

* a breezy and cool start to autumn *

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