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For the 13th consecutive year, we in the state climate office have evaluated the myriad daily, monthly, and annual observations gathered across New Jersey during the course of the year to choose what we feel were the most significant and impactful 10 weather and climate events of 2021. More about each event can be found in the monthly narratives and the special Post-tropical Cyclone Ida report posted on our website. You might be tempted to rearrange the rankings, particularly as some of the events on the list may have affected you more than others ranked higher. Or perhaps you best recall one that didn't make the list. That's the enjoyment and frustration of lists! Unless stated otherwise, statewide values are based on an average of several dozen stations. The period of record for monthly, seasonal, and annual departures is 1991–2020; while for extremes and rankings it is from 1895–present. Observations are mainly drawn from National Weather Service Cooperative Observing Program stations, Rutgers NJ Weather Network stations, and NJ Community Collaborative Rain, Hail, and Snow Network locations.

October was the second mildest on record in the Garden State since records commenced in 1895. This follows on the heels of the 11th warmest September, leaving most residents wondering when cool weather would arrive and leaves would turn and fall. For the first time since at least 1900, not a single weather observing station in New Jersey recorded a freezing low temperature on any day in either September or, as is climatologically most common, October. All of this resulted in a leaf season that was delayed by one to two weeks.

The statewide average October temperature of 61.1° was 5.7° above the 1991–2020 normal, a mark only surpassed in 2007. The average daily maximum of 70.1° (+4.3°) ranked 5th mildest (tied with 1920), and the average minimum of 52.0° (+7.1°) tied with 2007 as the mildest. These temperatures are close to what Norfolk, Virginia, normally experiences in October. In fact, despite the mean temperature normally declining 11.5° from September to October, this year’s mean was warmer than four previous Septembers since 1895 and the minimum was milder than 14 earlier Septembers. The state’s three climate divisions all ranked second mildest, with the north at 59.0° (+5.7°), south 62.3° (+5.8°), and coastal 63.2° (+5.6°).

Post tropical storm Ida moved across the Garden State during the afternoon of September 1st into the early hours of the 2nd. It brought with it torrential rainfall, leading to flash and river flooding that took the lives of approximately 30 individuals and the rescue of countless more from raging waters. Additionally, it brought three tornadoes to southwestern and central areas, including the first EF-3 twister to strike New Jersey in 31 years. There were only minor injuries and no deaths from the tornadoes.

Ida developed in the Caribbean, being named a tropical storm on August 26th. From there, it moved northwestward, attaining hurricane status on the 27th as it passed over extreme western Cuba and moved into the Gulf of Mexico. It maintained a steady course as it strengthened into a major category 4 hurricane, making landfall in Louisiana on the 29th with sustained one-minute wind speeds as high as 150 mph. Once inland, winds diminished rather quickly but rainfall associated with the tempest remained heavy as the storm began to curve toward the northeast. This track remained quite steady as the storm weakened to a tropical depression on the 30th and became an extratropical low-pressure system as it approached the central Appalachians. On September 1st, Ida’s remnants merged with an advancing cold front as the system entered the Mid-Atlantic and crossed New Jersey before moving into southeast New England on the 2nd.

Wow, what a month. July 2021 provided a never-ending cascade of weather events, including a tropical storm, a record-tying number of tornadoes, large hail, flash floods, hot days, chilly nights, smoke-filled skies, and on the last day of the month, perhaps the nicest day of the summer. The statewide average precipitation of 7.59” was 2.88” above the 1991–2020 normal and ranked 8th wettest of all Julys back to 1895. It was the wettest July since 1975 and second wettest in almost 50 years. The northern portion of the state averaged 8.16” which was 3.44” above normal. The south averaged 7.36” which was 2.62” above normal.

The average temperature of 75.8° was 0.4° above the 1991–2020 normal, but 1.9° above the 1895–2021 average. This ranked as the 24th warmest July since 1895. 13 of the 25 warmest Julys in the past 127 years have occurred since 2002. The nine July tornadoes is the most in a month since official records began in 1950. Tropical Storm Elsa was the earliest fifth storm of any season on record in the Atlantic basin. Read on for details on this potpourri of weather happenings.

Weather often varies from week-to-week and even day-to-day during the spring transition season. Such was certainly the case in spring 2021, as will be recapped later in this report. However, when it came to such “weather indecision,” May 2021 took the cake. Starting off somewhat damp with seasonable temperatures, a prolonged period of exceedingly dry weather ensued, first accompanied by cooler-than-normal temperatures and frosty mornings, and later by summer-like heat. As several wildfires broke out and soil moisture vanished, concerns of early-summer drought arose. Then along came one of the coolest Memorial Day weekends on record, accompanied by more than an average May’s worth of rain in some locations. This led to frequent decision making amongst farmers, gardeners, water resource managers, utility companies and customers, and day trippers. All were left wondering what might come next! Cicadas perhaps?

With the thermometer up and down throughout May, the statewide average temperature of 61.0° was just 0.2° below the new 1991–2020 normal. This ranked as the 47th mildest May since 1895. The average maximum of 73.0° was 0.7° above normal, while the 49.0° average minimum was 1.2° below normal. This is illustrative of a month that had many clear days and cool nights with low humidity. Despite dry conditions for most of the month, monthly precipitation came in close to normal, averaging 3.95” across NJ. This is 0.20” above normal, ranking 48th wettest of the past 127 years. Far south and west central areas were driest, while the central coast and northeast saw the most rain. Unlike last May, no snow was observed.