Upwelling Events On Long Beach Island

After a string of upwelling events this summer, some that could rank towards the top of historic records, everyone from anglers to surfers and bathers are asking, “Why’s the surf so cold?”

Attaching a thermometer to the back of a casting lure is a great way to monitor the water temperature when fishing.

Growing up on LBI, I’ve experienced our changing waters both fishing and surfing since a young age. Then in Oceanography Classes at Stockton College I learned more about our unique Cold Pool and the intricacies of our coastal dynamics. I’ve talked about it numerous times on my fishing report videos but never laid out a full blog post to comprehensively share information on the topic of upwelling on Long Beach Island. Here it goes!

Photo: Casting Lure and Thermometer, Steve George, Night Strikes Guide Service

The Cold Pool

What is the source of the cold water?

The waters of the New York – New Jersey Bight (Cape May, NJ to Montauk, NY) are unique. It is arctic in the winter with water temps in the 30’s and it is tropical in the summer with water at times reaching the 80’s. These are some of the largest ranging ocean temperatures in the world.

The waters change over the season…

WINTER: During the coldest months of the calendar (December–March) the water is well-mixed.

SPRING: April and May are the spring transitional months when the days get longer and the weather patterns calm. During this time the ocean’s surface temperature warms and stratification occurs creating a two layer summer ocean.

SUMMER: All summer, June/July/August/September the surface layer remains warm, but the bottom layer remains cold. This cold bottom water is known as The Bight’s Cold Pool.

This cold dense blanket is a vital part of our ecosystem supporting the diverse fisheries. Anglers can catch warm water species (mahi, marlin, wahoo, cobia, tuna, etc.) on the surface or upper water column and at that same exact location bottom fishing for cold water species (flounder, ling, cod, black sea bass, etc.)

FALL: The fall transitional months (October and November) the days get shorter, the surface cools and more frequent storms mix the ocean. The stratification breaks down.

The seasonality of ocean temperatures and the detailing of spring/summer stratification.

Looking at the graphic, the seasonality of ocean temperatures, take note of the stratification in June – August! It’s the time with the most radical temperature range and that is when the upwelling events pack the biggest cold punch!

Upwelling Events As A Result Of Ekman Transport

Let’s dive into the work of Vagn Ekman, a Swedish oceanographer who in the early 1900’s observed icebergs did not drift in the same direction as the wind. Through his study of fluid dynamics and commitment to physics he published his theory, The Ekman Spiral, which detailed the Coriolis Effect [due to planetary rotation objects in motion in the Northern hemisphere deflect clockwise, opposite in the southern hemisphere] in the ocean.

Part of his theory, Ekman Transport details the wind’s influence on driving and dragging surface waters at 90º from the direction of the wind due to the Coriolis force. Water displaced is replenished. Diverging waters due to Ekman transport create a void which in turn acts like a suction, upwelling deep sea water. In the exact opposite way downwelling occurs. Both of which have significant impacts on the world’s oceans.

Depending on the wind’s direction, duration, speed and area, these downwelling or upwelling events can range from none existent or minor to major.

The causes of upwelling graphic by the NWS.

Late July’s & Early August Upwelling Events – The Cold Water Event Recipe

Storm fronts and coastal storms largely drive the Mid-Atlantic weather. However in the summer it’s common for those patterns to break down and the “Bermuda High” takes over. Long Beach Island then gets its daily southerly sea breezes that at times can be very strong. These winds cause the surface waters to be pushed offshore making cold bottom waters upwell.

Due to persistent and prolonged southerly – southwesterly winds from high pressure in control of the Western Atlantic (around about Bermuda) and a lingering inland trough, a round of significant upwelling events took place in mid to late July 2022.

The lack of frontal system activity held the pattern and upwelling continued. There were numerous upwelling events one after another with a climactic ending, a much stronger event late in the month. The ice cold waters bounced back but it didn’t last long. Another upwelling event took place August 7-10th which is shown in the chart below. Temperatures were recorded by local anglers even colder, mid to low 50’s.

Barnegat Light water temperatures 8/4-8/10.

Central NJ Water Data

More local monitoring and a better buoy network would be nice but we must be happy and utilize what we have.

Barnegat Light USGS Station 01409125 – This tide and temperature station is uniquely located at Barnegat Inlet where it records the Barnegat Bay waters on the outgoing – ebb tide and ocean waters on the incoming – flood tide.

*Note the recorded data at this gauge/site can be influenced especially during low tide, it’s common to see LBI surf temperatures 2-4 degrees colder then recorded here. It is a great resource so long as you read it properly! The warmest (highest high) was at the end of the ebb current, August 9th at 3:37PM and the coldest (lowest low) was at the end of the flood current, August 9th at 9:49PM. The dropping lower lows from 8/6-8/10 is the upwelling event in the ocean taking place and progressing.

NOAA Waverider Buoy 44091 – The 44091 buoy is 15nm offshore of Barnegat Light, so it does not record the nearshore coastal upwelling data. It does however give a great read into the ocean surface temperatures. These waters will get pushed in with north and north east winds creating a downwelling event.

Atlantic City Steel Pier’s Station 8534720 – The Atlantic City Steel Pier data is what’s most commonly shows on the news. It’s an accurate surf temperature for general purposed. However, it’s not always a great read for the LBI surf. AC has a much more southerly facing beach and also Absecon Inlet. A persistent south wind can pile up the Absecon Bay’s outgoing waters against the beaches in close proximity and therefore read slightly warmer.

Better Your Catching When Summertime Fishing

Anglers who know about the upwelling phenomenon and the reasons why it occurs better understand the local area’s dynamics. Furthermore anglers who are mindful of and use water temperature to their advantage more effectively plan, alter and abort fishing trips.

Upwelling events are common for Long Beach Island. We all love that they offer a break from the hot and humid mainland. The surf and the sea breeze is the lure of the shore! Make the most of it and enjoy fishing!


Author: FishHead.Greg

A Long Beach Island native with life long experience fishing and navigating the local waters, Greg is a distinguished Master Captain (the highest qualified operator license), holding a US Coast Guard Masters 50T Near Coastal License with Towing Endorsement. Raised in and now managing his family's bait and tackle business, Fishermans Headquarters (Since 1962, The Saltwater Fishing Bait & Tackle Experts) Greg is daily immersed in fishing. He is the Chief Contributor of FishingLBI.com (Long Beach Island's best fishing report blog) as well as the Admin for the shop's social media pages (on Instagram and Facebook). Be sure to follow!

1 thought on “Upwelling Events On Long Beach Island”

  1. Really interesting. My friend and I were out yesterday and asking this exact question about why the water was so cold!

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