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Meteorologist explains June gloom

| May 29, 2025 | 0 Comments

Last month we checked in with our favorite local meteorologist, Autumn Robertson, at Spectrum News 1, to learn about “June Gloom” and how it affects our town. She took time out of her busy schedule to explain the science of our June weather.

Autum Robertson of Spectrum News 1

Ms. Robertson, what is June gloom?

“June Gloom” or “May Gray” is a colloquial term used to reference our SoCal-specific spring weather pattern. During this time of year, a ridge of high pressure along the West Coast tends to be the dominant weather feature. Air under this high pressure sinks, compresses and quickly heats, leading to our hot afternoons. The shelf waters off the Pacific Ocean, however, do not warm as quickly as land and remain cool into the summer months.

As this warmer air aloft sits above the cooler, moist air of the Pacific, an inversion layer forms trapping that cooler air at the surface. This interaction between the two air masses is what we refer to as the marine layer.

The warm air aloft eventually cools and condenses once it reaches the saturation point, leading to the formation of flat stratiform clouds, or the “gloom” that we see in the morning and afternoons.

You may also hear the term “Catalina Eddy” used in forecasting from time to time. This is an offshore circulation that forms when a thermal low develops in conjunction with high pressure aloft in the Pacific. The pressure gradient that forms helps drive the cooler air inland, and you can usually see the swirl of the eddy on satellite during the early hours of the morning off the Southern California coast.

Do we experience the gloom in a different way being that we are inland (Larchmont Boulevard/Hancock Park) as compared to people who live closer to the ocean?

The lowcloud deck will travel as far east as the Antelope Valley when the onshore flow is strong enough and high pressure aloft is weaker, limiting the warmth and sunshine we would usually feel during the day. This rising cloud deck is what we refer to as a deep marine layer, leading to slow daytime clearing across the Greater Los Angeles area. Sometimes mist and drizzle can form within the deeper marine layer, leading to a damp morning commute.

These clouds usually clear east to west, but on some days, “reverse clearing” occurs, and the beach communities will see the sunshine first. Under particularly strong ridges of high pressure, we tend to get a more “shallow” marine layer. The strong downward forcing of air squishes that marine layer to the surface, and any fog will stay confined to the coastline. This is why, on some unseasonably hot days in the spring, the beaches will stay much cooler and “socked in” compared to neighboring communities just a few miles inland.

JUNE GLOOM hovers over the Pacific Ocean looking out west from the Griffith Observatory in the Hollywood Hills.

Do you think the June gloom will last longer this summer, or shorter than other summers due to our current weather?

We tend to stay locked into this pattern for several days in spring and early summer, and it can be tough to forecast how many gray days we will see this far out. However, a persistent trough of low pressure offshore could significantly affect our weather pattern in the long term. The onshore flow increases, deepening that marine layer and leading to slow afternoon clearing and cooler-than-average temperatures. An active northwestern storm pattern this June could ultimately determine how many gray days we’ll see in the near future. 

Anything else you would like to say about it?

This weather pattern is not limited to the spring months. It can (and often does) occur year-round! It all depends on how the weather systems move around us.

And how do you enjoy your June, (gloom or not)?

Knowing that the aggressive summertime heat is soon to come, I love to take advantage of the cooler weather and the monotony of the daily clouds! On some trails, you can hike above the marine layer and take in the heaven-like views. It’s also slightly warmer higher up due to the temperature inversion. It’s really fascinating to see and experience. We can get so spoiled with the SoCal sunshine, and gray days may seem like a drag, but I love finding the beauty in everything Mother Nature brings us.

Category: News

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