The Finger Lakes is heading into the most dangerous stretch of heat so far this summer, with extreme heat warnings in effect across much of the region through Friday evening.
High temperatures will climb well into the 90s, and when combined with oppressive humidity, it will feel closer to 100 to 110 degrees in many communities. The National Weather Service says the heat will be especially dangerous because nights will stay warm and muggy, limiting relief for homes without air conditioning.
The worst of the heat is expected today and tomorrow, with Thursday likely to be the hottest day of the week. Some lower-elevation areas could flirt with 100 degrees before a cold front brings gradual relief this weekend.
The trade-off: The same hot and humid air fueling the heat wave will also support scattered thunderstorms at times. A few storms could be strong to severe, with gusty winds, frequent lightning and locally heavy downpours possible.
Today’s weather
Today will be hot, humid and uncomfortable from the start.
Most of the Finger Lakes and Central New York will climb into the low to mid-90s by afternoon. Heat index values are expected to top 100 degrees in many spots, with some areas reaching 105 to 110 degrees during the hottest part of the day.
Extreme heat warnings cover Ontario, Wayne, northern Cayuga, Yates, Seneca, southern Cayuga, Onondaga, Steuben, Schuyler, Chemung, Tompkins and surrounding counties. That includes communities such as Canandaigua, Newark, Penn Yan, Seneca Falls, Auburn, Syracuse, Watkins Glen, Ithaca, Corning and Elmira.
The warning runs through 8 p.m. Friday.
There may be a few showers or thunderstorms around early Wednesday, especially where overnight storms held together while moving out of the Great Lakes. Most areas should get into a mainly dry stretch for part of the day, but the atmosphere will remain unstable enough for isolated to scattered storms later.
Any storm that develops could produce heavy rain, gusty winds and frequent lightning. The bigger issue for most of the day, though, will be the heat.
Heat peaks Thursday
Thursday looks like the most intense day of the heat wave.
High pressure will remain locked in across the eastern United States, keeping a deep layer of hot air over the Finger Lakes, Rochester area, Syracuse area and much of Upstate New York. Temperatures in the mid-90s will be common, and a few normally warmer locations may get close to 100 degrees.
Humidity will remain high, with dew points in the low to mid-70s. That is the kind of humidity that makes the air feel heavy and prevents sweat from evaporating efficiently.
The result will be another day of dangerous heat index values. Many locations will feel like 104 to 108 degrees during the afternoon, with some central and southern areas again pushing toward 110.
Record highs could be challenged in several locations Wednesday and Thursday. Syracuse’s record high for July 1 is 94 degrees, set in 2018, while its July 2 record is 96 degrees, set in 1963. Binghamton and other interior locations may also come close to daily records.
Thunderstorm chances will continue Thursday, but coverage remains uncertain. The National Weather Service says forecast models have struggled with the placement and timing of storm clusters this week. That means some areas may stay mainly dry, while others could see a quick-moving round of storms.
Friday brings one more hot day
Friday will still be hot and humid, but it should not be quite as extreme as Wednesday and Thursday.
Highs will likely remain in the upper 80s to lower 90s across much of the Finger Lakes, with heat index values still ranging from the mid-90s to around 105 in some places. That is why the extreme heat warning continues through Friday evening.
The important change will be the approach of a cold front from the north and west. It will not bring an immediate break everywhere, but it should start pushing the worst of the heat and humidity away from the region heading into the weekend.
That front will also increase the chance for showers and thunderstorms. The setup favors scattered rounds of storms rather than one clean line, so timing will be difficult to pin down this far out.
Some storms could produce downpours. Localized flooding cannot be ruled out where storms repeatedly move over the same area.
Holiday weekend outlook
The Fourth of July weekend should bring some relief, but it will not feel cool.
Saturday will likely be less oppressive than the middle of the week, with highs generally in the mid to upper 80s. Humidity will still be noticeable, but heat index values should come down compared to Wednesday through Friday.
The frontal boundary may stall or slow down near the region, keeping showers and thunderstorms in the forecast. That does not mean the weekend is a washout. It means outdoor plans should include flexibility, especially during the afternoon and evening hours.
Saturday has the better chance for scattered storms as the front settles south. A few could be strong, and heavy rain will remain possible in the warm and humid air mass.
Sunday looks a bit more comfortable, with highs generally in the low to mid-80s. It will still be muggy, but the air should feel much more manageable compared with the dangerous heat earlier in the week.
Storm chances may continue Sunday, though coverage should depend on where the front ends up by then.
Heat safety
This is not ordinary summer heat.
The combination of temperatures in the 90s, high humidity and warm nights will significantly increase the risk of heat-related illness. People without air conditioning, older adults, young children, outdoor workers, athletes and anyone with health conditions will face the highest risk.
Drink water before you feel thirsty. Avoid strenuous outdoor work during the hottest part of the day. Move activities to the early morning or evening when possible. Wear lightweight, loose-fitting clothing and take frequent breaks in shade or air conditioning.
Check on neighbors, relatives and anyone who may not have reliable cooling. Pets should have shade and fresh water, and they should not be left in vehicles for any amount of time.
Know the difference between heat exhaustion and heat stroke. Heat exhaustion can cause heavy sweating, weakness, dizziness, nausea and headache. Heat stroke is more serious and can include confusion, loss of consciousness, hot skin and a very high body temperature.
Heat stroke is an emergency. Call 911 immediately.
What to watch
The forecast through Friday is high confidence on heat and humidity. The exact thunderstorm timing is lower confidence.
That is because storm clusters moving along the northern edge of the heat dome can be difficult to predict more than several hours in advance. Some may weaken before reaching the Finger Lakes. Others could hold together and bring gusty winds, lightning and torrential rainfall.
The best signal for more widespread storm chances comes this weekend as the ridge of high pressure weakens and a cold front moves into the Great Lakes and New York.
For now, the main message is simple: Wednesday through Friday will be dangerously hot across the Finger Lakes and Central New York. The weekend should bring gradual relief, but thunderstorms could complicate outdoor plans for the Fourth of July holiday period.
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