Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 5 · Portents, Comets
ग्रहचारः केतवश्च
पीतः शीते सिते वृष्टौ ग्रीष्मे लोहितभा रविः ।रोगानावृष्टिभयकृत् क्रमादुक्तो मुनीश्वर ॥ १० ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 10.
The Sun is yellow in the cold season, white in the rains, and shining red in summer. It brings illness, lack of rain and fear, in that order, O lord of sages.
Simple meaning: A yellow, white or red Sun in these seasons can bring illness, drought and fear in that order.
Classical view, not medical advice.
इन्द्रचापार्द्धमूर्तिस्तु भानुर्भूपविरोधकृत् ।
A half-rainbow Sun brings strife among kings. A hare-blood-red Sun means a battle soon.
मयूरपत्रसंकाशो द्वादशाब्दं न वर्षति ।
A peacock-feather Sun means no rain for twelve years. A Moon-like Sun can bring a change of king.
अर्के श्यामे कीटभयं भस्माभे राष्ट्रजं तथा ।
A dark Sun brings fear of insects. An ash Sun brings country trouble. A hole may mean harm for a great king.