Watchout for those sudden wind shifts like at about 5:10 pm. The anenometer falls into the lee of some wind shadow with west winds hence he sudden dropoff.
Everyone knows how to deal with a wind shift offshore if you are already riding a ways off the beach, right? They are not that uncommon with arriving cold fronts or winking out thermals around sunset. Best way to deal with it is to anticipate the shift through forecasts and watching for signs, but failing that, what do you do?
No ideas? Ok, I'll lead off then. If the wind is very close to offshore you will likely not do very much by using the kite as a sail on the water to make for shore. The reason is that you will be sailing largely parallel to shore up or down the coast. The times well in the past when I tried it, didn't get anywhere useful at all. Often with offshore winds at least in SE Florida, there will be pronounced lulls that will likely stall your kite and drop it on the water. The closer you are to shore the more likely this is to happen. Take pains to keep the kite flying if you need to ride in spurts or if necessary doing powered figure eights body dragging in with your board held in front of you on your feet. You may only get so far doing this depending on how weak and uneven the wind will become.
What to do? First, wear flotation like an impact vest. With this one choice alone you have largely removed drowning from the playing field as along as you remain conscious. Then you should be free to reduce the pressure in your leading edge to reduce the wind dragging your kite offshore. I usually securely tie my kite leash to a footstrap taking care of both my board and my lines allowing me to deal with the kite. I swim up to the kite parallel to but staying away from the line. I reduce the leading edge pressure (btw you can blow it back up to a point by mouth if you need to usually) to drop the wind drag of the kite. Then I grab a wing tip and start to sidestroke to shore. Depending on how far offshore you are you may be doing this for a while. I think my record is about two hours, really dumb and well in the past but there it is. I believe anyone kiting should have strong swimming and watermanship skills, but still wear an impact vest routinely.
Make sure you are wearing adequate exposure clothing for conditions and an extended period in the water. This means dramatically different clothing say comparing Key West to Jacksonville this time of year. We lost a kiter on an inland lake due to inadequate exposure clothing, no flotation among other factors in past months.
Lastly, and this is a big one. DO PROPER WEATHER PLANNING AND MONITORING!
Look upweather on the forecast, radar, satellite maps and real time winds to see if a strong frontal boundary in coming through. See just how powerful and nasty it is to that point. Estimate its speed of travel understanding that it is subject to change.
IF a powerful frontal boundary is coming in with the classic 90 degree wind shift, major wind spike and possibly violent squalls MAKE sure you are not on the water when it passes over. Have your kite well secured before the boundary and potential hazardous winds arrive. Go from your eta estimate and visible conditions. If in doubt, simple, don't go out.
A kiter was killed in CT a while back due to this cause. A couple of kiters spent many hours one cold night being blown out into the Gulf by a powerful offshore frontal wind in the Panhandle. If you really screw up and are caught out, DON'T let your kite drag you offshore and you may have very little time to act. If you have to choose, choose yourself and ditch the kite. If you are already too far from shore you have a hard choice. Some say never leave your kite once offshore as it is more visible and has flotation. If you are using an vest, the later point shouldn't matter all that much. There is a chance your kite can be recovered with a boat if you never leave the shore but your kite does. No such certainty about yourself however.
Input? This is a common phenomena, people need to commonly know how to try to deal with it.