“rains” used to be a reference to “the rainy season”. That usage has been enlarged to include how this article uses it.
> If you say Rains could last through the week
I would never say that.
>
Rain could last through the week means it will rain all week without stopping.
I would not make that assumption. You might, I wouldn’t.
It’s not an assumption it’s the proper use of the word. Also, having spent over 60 years in CO, I have heard the weatermen and others say “snows could last through the week” (or something similar) thousands of times.
Maybe your English teacher was affirmative action.
The winter snows are coming.
rainnoun
1. water that is condensed from the aqueous vapor in the atmosphere
and falls to earth in drops more than 1/50 inch (0.5 mm) in diameter.
Compare drizzle (def 6).2. a rainfall, rainstorm, or shower:
We had a light rain this afternoon.3. rains, the rainy season; seasonal rainfall, as in India.
4. weather marked by steady or frequent rainfall:
We had rain most of last summer.5. a heavy and continuous descent or inflicting of anything:
a rain of blows; a rain of vituperation.