Tomato blight can refer to early or late blight. Unfortunately, once these fungi infect your plants, they can spread rapidly. During some years, commercial and home growers alike can have their entire crop wiped out.
Both early and late blight affect tomatoes and similar plants, but they're caused by very different fungi. And though they're called "early" and "late" both diseases can occur at any time during the growing season.
I suggest reading more details on these fungal diseases so you can be informed of the best preventative growing practices. That's because certainly the old saying applies here:
An ounce of prevention is worth a pound of cure. -- Ben Franklin