And the word of the Lord brought down showers of favour upon Sodom and upon Gomorrah in order that they might work repentance, but they did not do so, but said: ‘Works of evil are not revealed before the Lord.’ Behold, therefore, brimstone and fire descended upon them from before the word of the Lord out of heaven.

Other Targums on Genesis xix. 24

F.T. (Gins. p. 12; see also p. 77): And the word of the Lord was bringing down upon the people of Sodom and of Gomorrah showers of favour in order that they might work repentance from their evil works, but they did not do so. But when they saw the showers they said, ‘Here is confirmation that evil works are not revealed before him’. And he turned to bring down on them brimstone and fire from before the Lord out of heaven.

Notes on Genesis xix. 24

That Sodom and Gomorrah were given a clear chance to repent agrees with the view that a similar opportunity was given to the generation of the flood; see the notes on Gen. vi. 3. The close connection between the two can be seen in Rashi's comments on Gen. vii. 12 and xix. 24: vii. 12: ‘And the rain was upon the earth: but later it says, And the waters prevailed exceedingly upon the earth … In fact when he poured it forth (first) he poured it forth with mercy, so that if they turned in repentance it would be a shower of blessing.