Tuesday’s forecast numbers are the ones commanding attention this morning — NWS Buffalo issued a Heat Advisory overnight covering every county across the Finger Lakes, running through Tuesday at 8:00 PM, and the reasoning behind it is worth understanding. A massive dome of high pressure centered over the upper Mississippi Valley is expanding east, with 850-millibar temperatures forecast to reach the 99th percentile for mid-July. That translates to heat indices in the mid-to-upper 90s across most of the region Tuesday, with low 100s possible in parts of the Genesee Valley and Finger Lakes proper.
Today is actually the more comfortable of the two days — though “comfortable” is relative. Skies are mainly clear this morning with temperatures in the mid-60s region-wide, humidity already running high. Highs climb to the upper 80s this afternoon, with Geneva topping near 88° and Watkins Glen reaching 92°. The saving grace today is that humidity stays somewhat in check, keeping heat indices mostly in the mid-80s to around 90. Light southerly winds of 3 to 6 mph won’t provide much relief but won’t make things worse.
Tuesday is where the heat advisory earns its weight. Highs surge into the low-to-mid 90s, with Ithaca and Canandaigua expected to reach 91° and 89° respectively. Rising humidity combines with those temperatures to push heat indices well above what the body handles comfortably. Stay hydrated, limit outdoor exertion during peak afternoon hours, and check on elderly neighbors and anyone without air conditioning.
Overnight tonight, lows hold in the mid-60s under clear skies — warm enough that it won’t feel like much relief coming through the windows.
Looking ahead, Wednesday drops back to the upper 80s with easing humidity, followed by a quieter stretch into mid-week. The pattern stays mainly dry through Thursday around 86°. By Friday the 17th, a slight chance of drizzle creeps in around 81°, with better rain chances — near 46 percent — arriving Saturday and continuing into Sunday. Stream flows across the region remain seasonably low, with Catharine Creek at Montour Falls running just 5 cfs — not unusual for mid-July, but worth noting for anyone using those waterways.
Weather Center forecast for the Finger Lakes region. Sourced from NWS, Open-Meteo, NWS Area Forecast Discussion, and USGS stream-flow data. Updated 6 AM, noon, and 6 PM ET.