I know that tomatoes split due to irregular watering. But since I cant prevent downpour of rain, what can I do to prevent or minimize splitting?
One of the most common methods often discussed in the many previous discussions here about splitting problems is to just harvest the fruit at the breaker (blush) stage and finish ripening it inside. That is a routine practice for many and especially effective when heavy rains are forecast.
In case anyone's not familiar with the breaker stage, here are a couple of charts which show the different stages of ripening.
Old chart slightly smaller here:
[Firefox pointed out that this did not open in a clean format, and offered to open it in Adobe instead: luckily, that version came up without errors.]
There are many varieties that seldom split. Some seed catelogs like Johnny's will indicate in the description if the variety is more resistant (less prone) to splitting. Just beware- some don't split because the skin is as tough as shoe leather.