The water's still cold, so I'm not planning to swim, okay?
Literal
Still water-temperature low [because-から] swim intention [topic-は] not-exist [dialect-んよ]?
んよ at the end is a dialectal softening particle, common in western Japanese dialects. つもりはない (have no intention of) is stronger than just 'don't want to.' 水温低い drops the copula — natural in casual speech. The overall tone is friendly and explanatory.