A quieter late-summer stretch is giving way to a wetter, more changeable pattern across the Finger Lakes and Central New York on Sunday, with showers and a few thunderstorms returning later in the day and an unsettled workweek lining up behind that change.
After a mainly dry start, clouds will thicken and humidity will climb, according to the National Weather Service offices in Buffalo and Binghamton. The first showers are expected to spread in from the northwest during the afternoon, with repeated rounds of rain and occasional thunderstorms remaining in the forecast through at least the middle of the week.
Sunday starts dry, then showers fill back in
Most of the region began Sunday on the quieter side of the forecast. High pressure that brought the clear, cooler weather at the end of Saturday was still close enough to support a mainly dry morning, and some valleys were expected to see patchy fog around daybreak before visibility improved.
That early calm is not expected to last through the full day. Both forecast offices point to a gradual increase in cloud cover and shower chances as a frontal zone strengthens across the Great Lakes and disturbances move through the broader northwest flow aloft. The shift is expected to happen in stages rather than all at once, with the higher chance of rain building from northwest to southeast through the afternoon and into the evening.
That means the western and northern Finger Lakes could see the first showers sooner than places farther east and south, while Central New York and the higher terrain may wait until later in the day for the more meaningful increase in coverage. The Binghamton office also allows for a few thunderstorms as that activity spreads in during the afternoon and evening.
Even so, Sunday does not look like a day dominated by severe weather. Extensive cloud cover is expected to keep instability limited, and both offices describe only isolated thunder potential rather than a widespread or well-organized storm event. The more likely outcome for much of the region is a mix of dry time, increasing clouds and scattered showers, with a few brief rumbles mixed in where the atmosphere can destabilize enough.
Temperatures should still recover into the upper 70s to low 80s across much of the Finger Lakes and Central New York despite the cloud increase, while the bigger change will be the return of stickier air after Saturday's more comfortable feel. By late day, it should feel more like the start of a humid early-September stretch than the dry break that closed out the weekend.
Sunday night and Monday keep the pattern unsettled
The broader forecast becomes less about one passing round of rain and more about a pattern that keeps finding ways to generate additional showers. Buffalo forecasters expect showers to continue Sunday night across Western New York, while areas from Rochester and the Finger Lakes eastward may get at least a temporary drier window as somewhat drier midlevel air works south out of Canada.
That does not amount to a full clearing trend. Both offices continue to point to plentiful low-level moisture, and that leaves room for fog to redevelop overnight and toward daybreak Monday, especially in the more typical valley locations. In other words, some communities may go from evening showers to a murky start Monday rather than into a clean dry reset.
Monday keeps the front nearby and allows rain chances to increase again as it edges back northeast. The Buffalo office describes a southwest-to-northeast increase in rain chances through Monday and Monday night, while the Binghamton office continues to carry scattered showers and thunderstorms through the day, especially during the afternoon and evening.
There are also signs that Monday may end up uneven from one community to the next. A few stretches of the day could stay largely dry, especially outside of the more persistent shower bands, but the region as a whole is moving into a pattern where dry windows may be temporary and hard to pin down far in advance. That makes the first half of the workweek look more unsettled than continuously rainy, but clearly less settled than the weekend that came before it.
Instability still appears fairly limited on Monday, which should keep the severe-weather signal lower at the start of the week. That matters because the forecast is distinguishing between ordinary rounds of showers and thunderstorms and the more closely watched environment that may arrive later.
Tuesday and Wednesday bear the closest watch
By Tuesday and especially Wednesday, both forecast offices shift to a more cautious tone. The expectation is that warmer, more humid air will deepen across the region while a stronger disturbance approaches, creating a setup that could support stronger thunderstorms if enough sunshine and instability develop between the rain episodes.
The signal is not identical from one day to the next. Binghamton forecasters describe Tuesday as having somewhat lower potential because the large-scale trigger may be weaker, even though isolated to scattered afternoon thunderstorms remain possible. If stronger cells do develop, the main concerns at this stage would be hail or gusty winds rather than a broad severe outbreak.
Wednesday is the day both offices highlight most clearly. Buffalo forecasters say the severe-weather risk may peak then as a stronger shortwave moves east through southern Canada and a warmer, more humid air mass remains in place over the eastern Great Lakes. Binghamton forecasters similarly describe Wednesday as the period with the strongest support aloft and the better shear profile.
The uncertainty is still important. Forecast confidence is higher that Wednesday will be active than it is on the exact evolution of that activity. If clouds and earlier showers limit daytime heating, some storms could stay more elevated, which would shift the main concern toward hail and localized downbursts. If the region gets warmer and destabilizes more fully, the range of possible hazards could broaden.
Heavy rain also becomes a more meaningful concern by later Wednesday and Wednesday night if storms organize and repeatedly redevelop over the same corridors. That does not mean flooding is locked in, but it does mean the midweek forecast carries a different level of attention than the weaker shower-and-isolated-thunder setup expected earlier in the week.
Late week may start to ease, but not all at once
There are at least some signs that the pattern could gradually loosen its grip after midweek. Buffalo forecasters indicate the frontal zone may begin slipping back to the south and west by Thursday and Friday, which would support a gradual decrease in rain chances across the eastern Great Lakes.
That later part of the forecast is less settled than the shorter-range periods, and Binghamton forecasters still leave room for daily shower chances even after Wednesday as cooler air aloft and lingering troughing could keep afternoon pop-up activity in play. So while the second half of the week may trend less active than the first half, neither office is signaling a sharp return to a fully dry stretch yet.
For now, the clearest progression is a dry start Sunday giving way to afternoon and evening showers, a humid and unsettled Monday, and a more closely watched Tuesday-Wednesday window as the atmosphere becomes more favorable for stronger storms. The strongest confidence remains on the overall shift back to a wetter, more changeable pattern across the Finger Lakes and Central New York, with the precise timing and intensity of individual rounds still likely to be refined in later forecasts.
Check the latest forecast at the FingerLakes1.com Weather Center.
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