It’s because the viral disease of
smallpox is followed by delirium due to high fever. In India, winter lasts till February. Since March, the weather
conditions start changing for hotter environment, implying scorching summer season ahead. This transition period
(March & April) in season and weather conditions is the time of prevalence of diseases like smallpox, fever etc.
Hence, major religious observance, Shitalashtami, comes near the advent of the hot season. Festival of Shilashtami
is observed every year on the eighth day of the bright half of the Hindu lunar month of Vaishakh (April-May) to
propitiate a jealous, spiteful goddess whose wrath is visited upon those who ignore and displease her. In northern
India this festival falls at the advent of the hottest time of year; the climate thus mirrors the heat and fevers
brought on by contact with Shitala herself, in her form as smallpox. Although Shitala is conceived as spiteful and
jealous, she cannot be ignored, since this will be sure to provoke her wrath. The literal meaning of her name,
“Cool One,” can be seen as an attempt to appease her wrath through flattery. Therefore, in order to pacify her
anger, the devotees offer cool liquids like cold mild and curd.