PISCATAWAY, N.J. — October was a tale of two half-months. Summer-like weather prevailed through Oct. 11, quickly transitioning to fall-like conditions on Oct. 12. Passage of the first strong cold front of the season was responsible for the change. Moderate to heavy rain accompanied the front in northwest New Jersey during the daytime hours of Oct. 11. That evening, and into the morning of Oct. 12, moisture from the remnants of once major Hurricane Michael ran up against the front and brought heavy rain to south Jersey. This one-two punch was followed on Oct. 17 by the first freezing temperatures of the season at a few locations and a more widespread freeze on Oct. 19.
Generally cool conditions prevailed the remainder of the month. The remnants of yet another major hurricane, Willa, provided energy and moisture to a quick-hitting nor’easter on the morning of Oct. 27 that brought some of the worst coastal flooding since Sandy in 2012. Michael was an Atlantic storm that made landfall in the Florida panhandle, while Willa was an eastern Pacific storm that came ashore on the west coast of Mexico.
Statewide, the average October temperature was 56.5°. This is 2.0° above the 1981–2010 average and ranks as the 24th warmest October since records were established in 1895. South Jersey (Mercer-Middlesex-Monmouth counties and all points south, except the immediate coast) was absolutely and comparatively milder than north Jersey, averaging 58.0° (+2.4°), versus 53.8° (+1.4°) up north.
Despite the two previously mentioned large rain events, statewide October precipitation was rather close to average. The total of 4.38 inches was 0.49 inches above average and ranks as the 34th wettest of the past 124 Octobers. South Jersey was a fair bit wetter than up north, averaging 4.66 inches (+1.03 inch) and ranking 29th wettest. North Jersey averaged 3.82 inches (-0.49 inches) and ranked 56th wettest. This is still above the 3.44-inch median October north Jersey precipitation, as monthly precipitation records are skewed toward values less than the mean.
— New Jersey State Climatologist