Targum Jonathan on 1 Kgs 18:37 explicitly states that Elijah prayed for rain.
Receive my prayer, Lord, with the fire;
receive my prayer, Lord, with rain;
and may this people know by your doing for them the sign,
that you, Lord, are God,
and by your loving them you are asking for them by your Memra
to bring them back to fear of you.
And they gave their divided heart.
קביל צלותי [בעותי] יוי באישׁתא
קביל צלותי [בעותי] יוי במטר
וידעון עמא הדין ארי במעבדך להון נסא
ארי את יוי הוא אלהים
ואת ברחמתך [ברחמותך] יתהון משׁתאיל להון במימרך
ואנון יהבו [יהבין] ית לבהון פליג
The Masoretic Text makes no mention of Elijah praying for rain, but James explicitly gives Elijah’s prayer for rain as a second example of the prophet’s effective prayer (5:18). Given James’ emphasis on “double mindedness” (δίψυχος) in the context of prayer (1:5-8, cf. v. 8), Targum Jonathan’s use of “divided heart” (לבהון פליג) is particularly interesting. Elijah’s prayer for drought and rain is not simply a hyperbolic example of effective prayer, but is instead an example of intercessory prayer for judgment and mercy for the sake of effecting repentance. Thus this example is wholly appropriate in the greater context of vv. 13-20, where prayer for the sick takes place in a context of repentance and confession.
Translation by D. J. Harrington & A. J. Saldarini, Targum Jonathan of the Former Prophets (Aramaic Bible 10; Wilmington, DE: Michael Glazier, 1987), 248-49. Aramaic text from the Comprehensive Aramaic Lexicon; brackets (e.g., [בעותי]) indicate variants given in Sperber’s Aramaic Bible (Leiden: Brill, 1959-73).