The Compendium of Caraka 6.3.44

6.3.44

saṃcitaṃ &pittamudriktaṃ śaradyādityatejasā/
jvaraṃ saṃjanayatyāśu tasya cānubalaḥ kaphaḥ//
&`pittamutkliṣṭaṃ' iti pā-.
&prakṛtyaiva visargasya tatra nānaśanādbhayam/
adbhiroṣadhibhiścaiva madhurābhiścitaḥ kaphaḥ//
&`tatprakṛtyā visargācca' iti pā-.
hemante, sūryasaṃtaptaḥ sa vasante prakupyati/
vasante śleṣmaṇā tasmājjvaraḥ samupajāyate//

accumulated and irritated pitta, through the sun's fire in autumn, / swiftly produces fever, and kapha is its secondary force.
By the very nature of the discharging season, there is no danger from fasting in that case. / Kapha accumulated by sweet waters and medicinal plants
in winter is heated by the sun and provoked in spring; / therefore fever arises through kapha in spring.