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