This is common. It usually happens to ripe or almost-ripe fruit after a heavy rain or heavy watering. Some varieties resist cracking better than others. Thin-skinned varieties are especially vulnerable. You can avoid most cracking by going out right before rain is predicted and picking any fruit that has started turning color and ripening them inside in a warm, shaded spot. Once a tomato shows even the smallest signs of color change, it is capable of ripening to full color off the vine as long as it doesn't get too cold.

There is one caveat. I find that, while any flavor deficit from early picking is subtle to undetectable in larger tomatoes, depending on one's own sensitivity to taste and smell, conditions of weather/ripening, and variety, and the difference is offset by the fact that tomatoes picked after lots of rain have a tendency to taste "watered down" anyway, I find there's a large difference in taste with most cherry tomatoes that are picked early. So I usually only pick the ones that are well on their way to full color and take my chances with splitting with the others. But any fruit that is very close to ripe should be taken off the vine before rain, IMO.

It's a judgment call and a matter of weighing pros and cons.

Also, some very thin-skinned cherries split from the simple stress of picking once they get ripe. They're usually pretty delicious, though, and there's no reason to be concerned about it unless you need to keep them or sell them. I usually just eat the split ones first. They usually don't make it out of the sink, as I'll just eat them while washing them.

Combination of moisture, degree of ripeness and variety. If the variety is prone to splitting you need to keep moisture a bit lower and pick as soon as they turn color. You probably have plants outside but if you would have plants in a high tunnel as I do you have more options. I still shy away from planting many Sun Gold and other splitter varieties and I never wet fruit after picking.

I always wash fruit after picking because I spray copper and serenade, and have never seen splitting due to it as long as the washing is gentle.

Okay. Thank you. I wash fruit right after picking.