The Compendium of Caraka 1.6.4_1

1.6.4_1

tatrādityasyodagayanamādānaṃ ca trīnṛtūñchiśirādīn grīṣmāntān vyavasyet varṣādīn punarhemantāntān dakṣiṇāyanaṃ visargaṃ ca //

Among them, the northern course of the sun and the debilitating period one should determine as the three seasons beginning with śiśira and ending with grīṣma; the southern course and the releasing period, moreover, as those beginning with varṣā and ending with hemanta.