I am shooting in a windy location for the next few days. I didn't pick it, and the location is not up to me, but the lights keep falling over because of the wind, and the bags are not able to hold them down because we cannot secure the bags on top of the legs without them slipping off. Does anyone else know how to do this? I tried watching videos on it but in the videos, the bags stay on.

Thanks for any information on it! I really appreciate it!

Ratchet straps. Gaffer tape. Bungee cord.

I put them on the inside leg. https://www.diyphotography.net/sandbags-101-types-of-sandbags-and-how-to-use-them-properly/

But in order to work they can’t touch the ground so you might need to use tape or other means mentioned to secure them. I find c-stands better for outdoor locations. When you factor the time and weight of deploying sand bags...

Okay thank you very much. I have used C-stands before, but this production is using the more extendable stands. The inside leg isn't big enough to fit a sandbag through because they want to heighten the lights as high as possible for this shoot, and this causes the stand to become much thinner on the buttom, if you want to go the highest. So it's hard to get a sandbag through the leg.

However, if I use gaf tape, the gaf tape keeps slowly peeling off though by the weight of the bag.

Okay thank you very much. I have used C-stands before, but this production is using the more extendable stands. The inside leg isn't big enough to fit a sandbag through because they want to heighten the lights as high as possible for this shoot, and this causes the stand to become much thinner on the buttom, if you want to go the highest. So it's hard to get a sandbag through the leg.

However, if I use gaf tape, the gaf tape keeps slowly peeling off though by the weight of the bag.
I'd get thin nylon rope from a hardware store. It's better suited to holding weight than tape is.

Normally, you attach the sandbags properly - cable ties are good, then gaffer as secondary attachment. I'm a bit surprised we're talking about this - weights and stability are usually what the junior/ass grades tend to do anyway? I like releasable cable ties - 300mm strong ones - they can do so many things. As a general rule - lots of weight, as low as possible, and as structurally secure as possible.

Get someone to hold them.

Ryan - I like this question!!!

Failure, in this caee, is likely to be very expensive.

Cost of the damage equipment, lost time in the shoot (may have to return another day), increased labor cost, etc.

Wind questions:
is it from one direction, numerous directions but within a range like, say, a quadrant (say 90º), or all over the map (360º)?

While placement of the bags inside the legs may be typicall, for best resistant to tipping the bag will be more effective when placed outside the leg.
T = Torque
W = Weight
D = distance
T = W x D (x = times)

Depending on how windy it is, like, really, really windy, then the legs must be spread out wider. Can’t do that? then Improvise!

Suggestions:
Plan A: Get some wood - 1 x 4 x 6 feet (2 meters?) Edit: 1-inch x 4-inches x 6 feet
Form a V with the point under one leg and the other two legs spaced on the outstreatched boards. Wire-tie them down. (concrete rebar tie-wire is fairly cheap. Drill holes through the wood to feed the tie-wire through.

If this isn’t enough, gest a sack of sand (from the big-box hardware store) and put on the V-end of the boards. Any rocks on site?

Plan B: Plywood
One can do the same setup with a sheet of 4 x 8 plywood.

Cheap or free wood source?
Search your local on-line want-ads. There are usually ads for Free used stuff.
Heck, even cinder blocks would be good weights. (approx 6H x 8W x 16L, in inches)

Plan C: anyone just standing around??? Put them to work holding the stands down and make sure they don’t tip over. If the stand tips, they need to get under it and cushion the fall.
[Just noticed that Donald beat me to this one!]

The key word is: IMPROVISE

Okay thanks! I managed to get the sand bags down secure and it's holding so far, although it wasn't as windy for today's shoot. But I will see how it holds up when it gets more windy again. The wind is coming from one direction.

The location has a three walls surrounding us, but the side where there is no wall, the wind is blowing in hard.

This is a really basic area where ryan’s rules fall down. Improvise, adapt and innovate. On the spot, with available materials. This is an area where you sink or swim, because by and large, it cannot be taught as each problem is unique. You simply stand there. Take in the problem and fix it. And yes, it may well mean you put a person on it, and that’s their job.

Don't be too hard on him. We all know improvising isn't has strong suit. I'd also assume this is another no budget, can't afford equipment, skeleton crew, project.

I just finished shooting outdoor amateur movie. My god the amount of energy and determination to deal with weather and every sort of issue is exhausting.

If using Lighting stands. putting the sandbags on the cross struts will work better than the legs themselves; the bags don't slide down., If working in really windy conditions, lashing the stand to a solid support, such as a lamp port or railings, tends to prevent damaged lights. .

Okay thanks. I wanted to put them on the cross struts before but there is barely enough space in there to put them. I could get smaller sandbags but then they would be too small for the wind. But I have taped the sandbags down with lots and lots of tape and so far it's holding...

The world survives on gaffer tape.

People rather spend money on a camera and save on things like light stands. You’re finding out in ideal conditions cheap light stands are fine, but outside in windy conditions you’ll discover why they are cheap.

The location has a three walls surrounding us, but the side where there is no wall, the wind is blowing in hard.

If it's strong enough to blow over the light stands, I'll bet the sound man is having a blast (pun intended).

I'm late to the party but this may be useful for future occasions:

I don't use sand bags at all. I have a number of Manfrotto L-Peso, 4.3kg Counterweights
https://www.manfrotto.com/uk-en/l-peso-4-3kg-counterweight-023/
Three of these if necessary, one on each foot, should do the trick. C-stands may be better than standard light stands if the ground is uneven.

They are much more compact cleaner and easier to handle than sandbags - though problematic if you need to fly to a location obviously :- )

Occasionally I also use the weight discs off of barbells. I attach them by tying nylon cord through the weight to stands and tripods. These are also very easy to carry if you simply sling a loop of cord on your shoulder and have the weights hanging down. Many weights have plastic coatings so they are not as likely to damage anything thats fragile. Lots of pre-owned on Ebay I would guess.

If you are not pushed for time and are on soft ground you can improvise using some heavy duty long tent pegs and nylon cord

Have you considered canopy weights for use in pop-up gazebos? They are shaped like elongated tubes that are meant to be wrapped around the legs (vs. draped over them), and include a velcro strap that keep them securely in place.
A 40 lb. weight in the center of gravity should work with nearly any light you could put on those lighter-weight stands. Now, if you've got a large modifier attached, like a 4' softbox, then you'll want a c-stand, plus weights, and possibly even a guy line attached higher up so that the top of the stand doesn't wiggle around.
Always keep some paracord in your kit, tent stakes are super handy when setting up on grass (for guy lines), ratchet straps, zip ties, and gaff tape. With that kit, you're ready to tackle anything.