National Weather Service forecasters in Miami are predicting Sunday morning could dip to 67 degrees as Canadian air makes its way south at the behest of the autumn-revved river of air 30,000 feet above Earth.
Overnight temperatures have not fallen into the 60s in West Palm Beach since May 26 when the low hit 68 degrees at Palm Beach International Airport.
The normal overnight low for this time of year is 72 degrees. That falls to 70 on Sunday.
“It’s still not a super strong cold front like we’ll see later in the year, but it’s stronger than the one we got after (Hurricane) Matthew passed and we had drier air move in,” said Andrew Hagen, a meteorologist with the NWS in Miami. “This month, the coldest low we’ve had in West Palm Beach was 73 degrees, so this will be the coldest this season.”
The high temperature on Sunday is forecast to reach about 80 degrees. The normal high for Oct. 23 is 84 degrees.
The cold front will feel like weather whiplash to people in some mid-Atlantic states and the northeast who are expecting to see high temperatures up to 20 degrees above what’s normal today and Wednesday.
Washington, D.C. is forecast to hit 85 degrees today when its normal high temperature for October 18 is 67 degrees. New York City could reach 82 degrees today, a whopping 18 degrees above what’s normal for this time of year.
The heat is courtesy a large clockwise swirling high-pressure system funneling warm air north and shoving the jet stream up into the Great Lakes. The looming cold front is expected to break that high pressure apart as it moves east, allowing the jet stream to make its dive south.
By Saturday, Washington, D.C.’s high temperature will be back to 63 degrees with New York seeing similar, more seasonal temperatures.
“It’s basically a big change in the whole weather pattern across North America,” said Ken Clark, an expert meteorologist with the Pennsylvania-based AccuWeather. “That’s kind of how October goes sometimes. There can be big swings in temperatures.”
Clark said forecast models are still unclear on exactly when the cold front will move into South Florida, but generally agree sometime Friday or Saturday.
With the lower temperatures will also be drier air. Hagen said rain chances are running just 20 to 30 percent through the weekend.
But don’t get excited just yet about the arrival of the South Florida’s dry season. It takes extended days of lower dew points and lower precipitation to formally mark an end to the rainy season.
“We haven’t officially declared that we are in the dry season,” Hagen said. “But the weather pattern has been looking more reminiscent of it.”
While South Florida awaits cooler temperatures, the National Hurricane Center is keeping its eye on a tropical disturbance southeast of the Bahamas that forecasters identified for possible development.
As of 2 p.m. Monday, the cluster of showers and cloudiness was given a 60 percent chance of forming into a tropical cyclone within 5 days. If it becomes a tropical storm, it would be named Otto.
Florida isn’t expected to be affected by the disturbance, no matter whether it fizzles or grows.
“It could have some impact on Bermuda later in the week,” Clark said. “But it doesn’t seem likely that it will bother Florida.”
As measured at Palm Beach International Airport
Normal daytime high Oct. 18-19: 85 degrees
Normal daytime high Oct. 20-25: 84 degrees
Normal overnight low Oct. 18-22: 71 degrees
Normal overnight low Oct. 23-26: 70 degrees
Average date of first 60-degree temperature: November 2