Sītavalāhakasutta

Sāvatthinidānaṁ. Ekamantaṁ nisinno kho so bhikkhu bhagavantaṁ etadavoca: “ko nu kho, bhante, hetu, ko paccayo, yenekadā sītaṁ hotī”ti? “Santi, bhikkhu, sītavalāhakā nāma devā. Tesaṁ yadā evaṁ hoti: ‘yannūna mayaṁ sakāya ratiyā vaseyyāmā’ti, tesaṁ taṁ cetopaṇidhimanvāya sītaṁ hoti. Ayaṁ kho, bhikkhu, hetu, ayaṁ paccayo, yenekadā sītaṁ hotī”ti. Tepaññāsamaṁ.

At Sāvatthī. Seated to one side, that mendicant said to the Buddha: “Sir, what is the cause, what is the reason why sometimes it becomes cool?” “Mendicant, there are what are called gods of the cool thunderclouds. Sometimes they think: ‘Why don’t we revel in our own kind of enjoyment?’ Then, in accordance with their wish, it becomes cool. This is the cause, this is the reason why sometimes it becomes cool.”