Record warm temperatures expected on Wednesday in NYC

High temperatures on Wednesday are expected to climb into the upper 80’s and lower 90’s in New York City, challenging daily and monthly records for October. Rising dew points will lead to heat index values into the mid 90’s during the afternoon.

The record high temperature on October 2nd in Central Park is 90 F, which will almost certainly be challenged. Records are similar at other reporting stations throughout the area. The all-time record high temperature for October in Central Park is 94 F, set in 1941.

One last summer-like ridge

A large ridge of high pressure sat over the Ohio Valley and Mid-Atlantic states for prolonged periods this summer, and it has continued to reappear this Autumn. September 2019 will end as one of the warmest Septembers in US history, with the majority of warmth emanating from those regions.

A ridge of high pressure in this position helps to facilitate a warm, humid pattern across the Eastern United States. When these ridges amplify and slow down, they can lead to stretches of anomalous warmth and draw in humidity and moisture from multiple sources.

This ridge was no different. Thus far, the NYC Metro Area has been able to escape the worst of the heat, but the same cannot be said for our neighbors to the south (we’re looking at you, Washington).

Backdoor front will signal pattern change

The temperature forecast on Wednesday is very complicated. A frontal boundary will be sinking southward from New England, with a wind shift bringing cooler air southward from the Gulf of Maine. Parts of Connecticut and Southeast New York will see a 10-15 degree temperature drop during the afternoon hours.

Exactly where this front sets up during the afternoon will be key. Areas just south of the front will see enhanced warmth and humidity, and that could be just enough to push parts of New Jersey and the NYC Metro over 90 and near all time monthly record highs.

By the latter half of the week, temperatures will begin trending downward. Multiple disturbances will ride over the top of the ridge and begin de-amplifying it, allowing cooler air to move in and bringing an end to the warmth and humidity.

This pattern, with a more active flow and cooler temperatures, appears likely to settle in for at least a week or two as we move into the middle part of October.