Learn Swedish: Om torkan fortsätter, blir skörden mycket dålig. - If the drought continues, the harvest will be very bad.

This is the famous V2 (verb-second) rule in action. The entire if-clause (Om torkan fortsätter) counts as the first block of information. Because the verb must come in the second position, the main verb (blir) has to step in right after the comma, pushing the subject (skörden) to the other side of the verb.

The English translation says 'will be very bad', so why do we use the present tense verb blir instead of a future tense like kommer att bli?

In Swedish conditional sentences, it is perfectly normal to use the present tense in the main clause to describe a future outcome. While kommer skörden att bli is also grammatically correct, simply using the present tense (blir) is usually preferred because it is shorter and more natural.

Could I use är instead of blir here to mean 'is very bad'?

You could, but it changes the meaning slightly. Är (is) makes it sound like the harvest is already bad right now. Blir (becomes / will be) emphasizes the transition or the future consequence: a bad harvest is the result that will happen if the drought continues.

Is the word torkan related to the verb att torka (to dry)?