California Diving Weather

CopyRight @ 1997

Waves and the Weather Radio

So how can you tell if the conditions are divable, without going out in the ocean? Good luck. That question has been asked by mariners for at least the last 8000 years that people have used boats. It has often been a life or death question. I try not to carry it that far when sport diving, but it is a question that most divers are asking themselves as they get on the boat or plan for a dive. Here are some patterns to look for or consider, when diving in California.

The weather radio is one of the best bets. A problem though is that it can be hard to interpret. Also, weather above Point Conception is going to be a different issue than below it. All discussion of weather in California, must take this into account.

Point Conception is about 130 miles north of Los Angeles. It is where the coast turns firmly north after the various orientations of the southern coast. Past Point Conception, the coast just continues north until you get to Alaska. This makes the coast much more exposed in the north than in the south. If there is weather, you can pretty much forget diving from shore in the north. Monterey Bay might be an exception. If there is some weather and you do not mind rough water, there can be diving in deeper water.
South of Point Conception, where most divers go, is a different story. The weather radio can give some idea of what is coming from the north. If it is small craft warnings above Point Conception, but not below, it should be ok going out to the northern islands.
Listen for the period of the waves. This is critical. If they are at 10 second intervals, it could be rough. Even 3 to 4 feet at 10 seconds is rough. Under 10 seconds, forget boating. By the time it is 12 second intervals, 3 to 4 feet may be fine. If the period gets up to 13 or 14 seconds, it is probably a ground swell and may not effect boating much at all, even if the waves are pretty big. Protected areas at the islands may be fine for diving.
The reports from the different weather buoys and recording stations have different significance, depending on where you want to go. If you plan to go to the northern islands, Point Arguello and Point Conception buoys can tell you what the swell is coming down the coast. The Santa Barbara Channel buoy will give an idea of what weather you will hit on the way to the more southern islands.
One problem with using the weather radio is that it is not completely accurate. It's pretty good, but time and again, it has suggested that the weather is going to be rough, but when we get to the dock, it looks ok. You go out and say "where's this weather you're talking about"? You cannot rely on their report to tell the whole story. You must interpret it. They more often overstate the weather than understate it.

Now there are internet sites that give the local marine weather, open ocean weather buoy reports, graphical wave analysis of the region and various other fancy ways to describe what the weather seems to be. Remember though, the bottom line is that this is weather coming from across the Pacific Ocean and presently it is still not accurately forecast. For the El Nino season, the weather people plan to do weather observations from aircraft sent over the ocean.

In California, the waves may come from the south, west or north, but the weather is going to come mostly from the north. The prevailing wind is from the north as well. When weather is here though, it is going to spiral such that the wind is actually heading south to north. A meteorology instructor at Cal State University at Humbolt ended his class by saying that if the stacks at the pulp mills blow north, it's rain. Otherwise it will be dry.

For shore diving, 2 to 3 foot waves are likely to be divable. If it gets to 2 to 4 foot waves, it is not likely to be fun. In winter, this may still be good vis though, so if you handle waves well, it may still be a dive. Watch it and watch your sets for a while before entering.

In summer, before things calm down much, a skipper from Ventura that goes out on a sorta rough day, is likely to go to the ocean side of Anacapa or Santa Cruz Islands to get away from the swell from the north. It may be a rough ride out, but calm diving. It may also make it calm enough to cross over to Santa Rosa island, though that will be a rough crossing. Coming back should be with the weather at your stern.

The winds pick up in the afternoon. If they calm down in the evening, it should be good. If they are blowing at midnight, don't plan on diving the outer islands. If they are blowing in the morning, it is probably spring and good luck.

Hey. Just go to the harbor and see how the flags are blowing.

Seasonal Changes

Spring is here. The sun is out. It's warm. It's beautiful. Forget diving. This is a common mistake made by divers. When the weather is starting to get nice, don't go, diving. Wait. Well, go diving, but be prepared for poor conditions.

The way I look at it, in California, the diving year could be said to start in spring. There are two factors to consider in spring. The first is the wind. The second is the algae bloom.

The diving in spring can be excellent. I have dove at Wilson Rock, San Miguel Island in the middle of March. Of course, the skipper of the Truth did say that we should tell out friends about it, because they would not believe us. In spring, the wind blows. At Catalina and the coast below Point Conception, that may or may not matter too much. Above Point Conception, if the spring winds are blowing, diving is unlikely to be advisable. I got to the cliffs above the water near Fort Ross one day in spring. I wanted to dive, but put it this way. Throw your mask off the cliff and it is likely to come back and hit you in the face. You cannot open your eyes without shades to protect them.
Also, but unrelated to local winds, the biggest ground swells that I have seen, were usually in spring. I was scheduled to go to Santa Cruz Island one week. This was the Sea Packer, about a 60 foot vessel. It was too rough and windy, so the trip was re-scheduled for the next weekend. It was rough again, but we went anyway. We were heading into the swell when we came to some mountain waves. The skipper mis-timed the wave by just a bit. The anchor flew into the air and came back down on the deck. we turned around. From top to bottom, I would estimate that these swell were over 30 feet. It is hard to say in feet though, but they are huge.

It's spring. Love is in the air. The algae are awake and horny. Some of the algae are in their diploid stage. Most are in their haploid stage. They are all dumping huge quantities of spores in the water. In Southern California it may cut vis to 20 feet or much less and make things yellowish brown. Above Point Conception, it is likely to make things into a brown soup with vis at 5 feet or less. This is not constant and is likely to happen until the end of June. If you look out though the waves and it is yellowish, the vis a bit deeper is probably gone.

Truthfully, I have done a lot of diving in spring and it is often good, but now in my dotage, come spring, I focus on other things.

Summer is the start of the good California diving. The wind is calming down and the algae is busy growing more than reproducing. As the seasons move to fall, the conditions continue to get calmer and the water clearer. Remember, this is a long coast. In Southern California, summer weather may start around May 1. Up on the North Coast, summer may not start for another month or so.

November is my favorite month for diving in California. The summer swell is completely gone and it tends to be calm. Vis gets excellent with 100 foot days fairly common in places at the islands. It tends to be warm during the day, especially below Point Conception and it is comfortably warm for the night diving.

This is the start of the season of the Santana Winds though. Sometimes mis-called the Santa Anna's, these are really the Santanas. "Devil Winds" as the Spanish called them. They come howling down from the high deserts and warm as they drop in elevation. Their main effect is below Point Conception. They can make for the best and the worst diving conditions. Near shore, they can make the water calm. They can blow off the warm upper water and create a cold upwelling. This was when I saw 200 feet of vis at Malibu. (Note: divers, look at the water temp. If it suddenly drops about 5 degrees on the coast, go diving.) If the winds are mild, it makes the ocean calm and the air balmy. Usually, these winds come down to the ocean about 60 miles out. The problem is when they drop down closer. Usually weather comes from offshore. In the morning calm, a boat can go out against the weather and depend on coming back with it in the afternoon when things pick up. In Santana conditions, a boat may have to beat its way back to shore. While these can cause problems anywhere off Southern California, it is at Catalina where they can get particularly dangerous. If you are at Catalina and you smell sage from the desert, run for it. Get behind the island. You may have to hide for more than a day, but you better hide or have it together to run back across the channel. This is why the Coast Guard recommends a boat that is minimum 40 feet out here. It gets wild. In the worse winds, it may destroy the boats in Avalon Harbor on Catalina. This is not an overwhelming hazard, but it is one of the worst local hazards a skipper must know about.
The Santana winds create the fire season in Southern California. When these fast dry winds blow. brush fires move so fast that the fire crews cannot keep up with them. I have seen them blow a fire helicopter straight backwards. If houses light, the flames may jump over one house to the next and leave the one in between undamaged. Note that the Northridge earthquake occurred the one week that winter that the Santanas were not really blowing. Much of the San Fernando Valley might have burned otherwise.

Most of the time though, the winter diving is great. It is calm with good visibility. There are storms occasionally. It is different from year to year. It can be good diving during a storm. The day after the storm passes though, there is usually wind. I skip that. After December, it starts to get cool. Bring warm out of water gear for serious night diving. It gets chill. Heck, bring it for day diving as well. January and February are generally good months to dive.
Then comes March. At some point the wind is going to start blowing. It is spring again. Well, by then I need a break.

Back To Start