This legend has been interpreted to be a mythological conflation of a seasonal and astronomical event: The heliacal rising of Sirius (with which Tishtrya is associated) occurred in July, just before the hottest and driest time of the year.
A mythological explanation of the heliacal setting of Sirius is only alluded to in the Avesta: In Yasht 18.5-6,[REF] Apaosha is contrasted with the bringers of prosperity, that is, Tishtrya and his assistants Vata and Khwarrah.