Here are some ideas haven't been listed yet
- Allow nouns denoting weather phenomena to form clauses by themselves
- Use an existential construction
- Make the subject a location
- Use an all-purpose weather verb
Weather noun clauses
If a normal transitive clause looks something like the following, then a weather clause can just be a noun by itself.
student-NOM book-ACC read-past-3sg
the student read the book
Here, the noun appears in the nominative case, which tends to be unmarked cross-linguistically.
It's raining/was raining/will rain
This way, it can be modified with adjectives just as it normally would be.
It's raining a lot/It's pouring/It was raining a lot/...
Use an existential construction
Ceqli, or at least an old version of Ceqli from years ago, uses an existential construction.
Make the subject a location
I think this is similar to Circeus' example, but I can't tell whether it's identical or not. If it's identical, I'll remove it.
Locative subjects are perhaps uncommon or unattested cross-linguistically, but in principle nothing stops you from making the weather verbs intransitive verbs whose subject is the location where the weather is happening.
It was raining here.
Spain-NOM principally plain-LOC rain-pres-3sg.
The rain in Spain falls mainly on the plain.
Lit: Spain rains mainly at the plain.
So the few references I can find to locative subjects are mainly things like this, which describe locations moving to or appearing in the first position in a clause rather than verbs whose subject position has a locative flavor.
All-purpose weather verb
Have a verb that means to be the weather, and use it with the name of the weather phenomenon.
It's not cloudy.
This has the advantage of making questions about the weather resemble their declarative counterparts.
How is the weather?
how-much cloud-NOM weather-pres-3sg
How cloudy is it?