Why is Vaiśākha a holy month, and why do people set up water stalls (pyāū)?

the Purāṇas praise Vaiśākha as dear to Viṣṇu, and in the peak of summer, giving water is the month’s greatest dāna.

Vaiśākha (April–May) is called Mādhava māsa and is praised in the Vaiśākha Māhātmya as one of the most sacred months. Early-morning bathing, worship of Viṣṇu, and offering tulasī are recommended throughout. Akṣaya Tṛtīyā, Narasiṁha Jayantī, Buddha Pūrṇimā and, in many places, Paraśurāma Jayantī fall in it.

Because it is the hottest time of the year in much of India, the dāna of the month is about relief: water pots (matkās), pyāūs or water stalls on roads, sharbat, fans, umbrellas, sandals, curd-rice and seasonal fruit such as watermelon. Feeding birds and animals with bowls of water is also part of it. Some temples apply cooling sandal paste to the deity, as in the Candana Yātrā of Puri.

A simple way to keep Vaiśākha today: place a bowl of water for birds, keep cold water for delivery workers and passers-by, and give a matkā to someone who needs one.

Vaiśākha is also called Mādhava māsa · Source: Skanda Purāṇa (Vaiśākha Māhātmya)

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