Here in the Sacramento Valley we get some pretty thick fog during the winter and spring. How do you all stay safe(er) and (more) visible in the fog?

You do in fact get thick fog down there. My answer, more lights, brighter lights, blinking lights.

An Airzound might be useful. If they didn't see you, then honking at them with your Airzond might be your last resort. Some of those tule fog makes a simple intersection crossing dangerous and having your presence known with lights and sound will minimize the danger.

Bright, flashing lights front and rear; Airzound; and rear view mirror.

I got a neon green parka with wide reflective bands last winter.. road side workers safety gear.

Hmm Air Zounds as a Fog horn .. cars will have their window shut.

There were a couple of days of fog this week and I kept my lights on blinking. I figure the blinking will attract better than solid beams. It's rare to get fog where I live and luckily it spooked the drivers so they drove a bit slower and more cautiously than normal.

Fresno is pretty famous for it's tulie-fog also. It gets pretty thick here in the Valley. We get it about the same time y'all do. I recommend a very bright flashing strobe (something like the Planet Bike Super Flash); SOLAS reflective tape; and if you have the notion to, a neon jacket similar to what road workers use. AirZound can be helpful. If it's particularly thick, you may want to slow it down - don't go faster than your sightlines. Too bright of a headlight may be counterproductive as well.

Also, be careful not to overdo it... pneumonia is no fun.

Unless they are really blasting music, they'll still hear it.

You need a rear light setup that identifies you as a bicycle and permits some distance estimation.
Use 2 lights with some separation. Use one of blink and one on solid.
I see some cyclists with 2 lights on blink, usually out of phase; you cant judge distance with this setup.

If you use a front light on blink, make sure the frequency is high enough to notice. Some slower blinkies can have over 1/2 second between light phases, long enough for a car to miss you.

Make sure that you have some light visible from the side (for junctions).

In my part of Georgia, we tend to get some pretty thick fog in the Spring and Fall... especially around the many low lying creek beds. So it's important to use strategy to remain visible on a bike.

The main mistake that most riders make is that they rely only on lights to be seen. Wrong. People will spend tons of money on lights and blinkies... but they forget about their most useful safety tool. Reflective gear.

The best way to be seen is to use both lights and reflective materials to let the human brain identify you as a human on a slow moving vehicle. A single blinkie... no matter how bright... does not give the driver enough cues to allow their brain to instantly make that connection. They will see a blinking light and start to figure out what you are, but they are often very close to you by the time everything clicks in their brain and they make the identification.

So give the drivers some cues. Use lights and blinkies to grab their attention, and use strategically placed reflective gear to show them that you are a human on a bicycle.

I use a Planet Bike Super Flash as my rear blinkie because it puts out a retina searing flash and uses only two AAA batteries. The flash catches the driver's eye... but that's all that the flash is for. The flashing light doesn't allow the human brain to accurately establish distance... that's where the reflective gear comes in.

A good reflective vest highlights your torso and allows the driver's brain to QUICKLY identify you as a human. To see what constitutes a really good vest, look at what police and DOT road crews wear. They are brightly colored and have reflective stripes both horizontally and vertically oriented to show the shape of the human torso.

And the final piece of the puzzle... and the one that almost no rider wears... are reflective ankle bands. I consider these necessary... I'd give up my helmet before I'd give up my ankle bands. If I could use only one single piece of safety gear for night riding, it would be reflective ankle bands. When a driver sees these reflective bands bobbing up and down, it is obvious to their brain that it's a bicycle. And the bands are visible from a full 360 degrees.

And please don't use crappy reflective gear. If possible, buy SOLAS (Safety Of Life at Sea) reflective tape and clothing. SOLAS tape is available in adhesive and sew-on varieties... and it is good stuff. The adhesive tape sticks to cloth, vinyl, cordura, and metal. And that crap is BRIGHT! It's like shining a headlight right back at a car.

I was unable to find a SOLAS vest geared towards atheletes... most SOLAS vests are geared toward survival or motorcycle riding, far too heavy to wear comfortably while bicycling. So I bought a lightweight reflective vest at Home Depot ($4.00) and had a tailor sew SOLAS tape over the cheap tape that the vest came with. It's perfect.

So please... don't strap a cheap blinkie on your seat stay and think you're safe.

strobes and tons of reflective tape on the bike and all clothing head to toe.

We get some lite and patchy fog here but if visibility is less than 100 yds. there is no way I will commute by bike.
There are just too many people driving that are already half blind to trust them to see me in dense fog. Heck, if they can't even avoid hitting parked cars they are not likely to avoid a bike either.

I have little experience riding in really dense fog, but in addition to all the comments about lighting I would add a rearview mirror might be a last line of defense against the sudden appearance of an oncoming car. I would probably check the rearview quite frequently. Also I would turn my radio or I-pod down really low, if not off.

I would also be on high alert for something oncoming, or in the road ahead. Naturally (for me) I would be riding slower.

I commute to downtown Sacramento from Folsom and have a good quality headlight with a flashing mode, a bright red rear blinkie attached to my backpack, reflective tape on my bike frame, and a hi-viz jacket with reflective accents.

There are a few mornings each Winter when the fog is just too thick. On those mornings I take my bike on the lightrail so that at least I can ride home in the evening.

sadly enough:

Tule Fog, obviously referenced to the plant "Tule" https://en.wikipedia.org/wiki/Schoenoplectus_acutus
which is about the only remnant of the days when
Tule Elk roamed
or when Tulare Lake was in it natural state.
we can be thankful for the Department of Reclamation for the removal of this environ
no what mostly remains is the Fog

and the ways of Tule use are long since gone...

well... here in Monterey we also have fog.
being on a foggy roadway is no doubt dangerous.

ironically riding at night out in the "Tules" with an 800 lumen light is fairly obvious.

I think the most dangerous times are in the early mornings. I'd try my best to simply be off the roadways, and hopefully a cyclist could ride on a separate bike path.

For me the most dangerous thing about cycling in fog is my glasses. They fog over - heavy beads of it -- and are hard to see through. More than once I've pulled them down my nose and gone without -- blurry is better than nothing.

Some great points on being seen in general--especially from Hydrated--here, but really, the problem with thick fog is that even the brightest lights get sucked up by the fog, and visibility doesn't happen soon enough. No one can see in the fog.

I think heavy fog is the most dangerous situation on the road, especially for cyclists, because we are overtaken very quickly by cars, popping out the gray with very little time for the drivers to notice, assess, and react. We have very little option but to rely on the quick reactions of drivers. That's a scary scenario to me.

I would recommend choosing routes carefully, and probably avoiding roads altogether unless they have a wide shoulder or bike lane. You'll have to be very vigilant and smart to stay safe in the fog.

In my limited bike experience in really thick fog, I agree with sudo bike: too much headlight can just blind you. It bounces back off the white in front of you. I've got a good bunch of boat experience that echoes this. I have ridden on a MUP in that kind of thick fog, and would continue to do so though I'm very concerned the whole time I'm doing it about a head on with an idiot going too fast. You basically have to navigate off the curb / trail edge and work with a VERY limited event horizon. I don't think I'd be on the road with cars in pea soup.

With fog that you can get a bit more visibility in and make out objects a bit further out to 20-50+yds, I agree with the trend of the posts towards reflectors and blinkies mattering a lot.