"Latter rain" in the Bible literally refers to spring rains.
"Former rain" refers to autumn rains. The terms latter and former
rains are used in the King James Version of the Bible. Some newer
translations, such as the New International Version, use the terms
autumn (or fall) and spring rains. Much of the Bible was addressed
initially to an audience living in a dry climate and heavily
dependent upon agriculture. Abundant harvests require both former
and latter rains. Thus, rain nearly always refers to a blessing.
"Latter rain" may also have symbolic allusions depending upon the
context of the passage that you are reading.