Adam Clarke on Matthew 16:3

The sky is red and lowering - The signs of fair and foul weather were observed in a similar manner among the Romans, and indeed among most other people. Many treatises have been written on the subject: thus a poet: -

Caeruleus pluviam denunciant, Igneus euros

Sin Maculae incipient Rutilo immiscerier Igni,

Omnia tunc pariter Vento Nimbisque videbis

Fervere Virg. Geor. i. l. 453 "If fiery red his glowing globe descends,

High winds and furious tempests he portends:

But if his cheeks are swoll'n with livid blue,

He bodes wet weather, by his watery hue

If dusky spots are varied on his brow,

And streak'd with red a troubled color show,

That sullen mixture shall at once declare,

Wind, rain, and storms, and elemental war

Dryden.