Passage 7.24.7
τὰ μὲν οὖν ἄλλα ἐπὶ τοῖς σεισμοῖς, ὅσοι μεγέθει τε ὑπερήρκασι καὶ ἐπὶ μήκιστον διικνοῦνται τῆς γῆς, προσημαίνειν ὁ θεὸς κατὰ τὰ αὐτὰ ὡς τὸ ἐπίπαν εἴωθεν---ἢ γὰρ ἐπομβρίαι συνεχεῖς ἢ αὐχμοὶ πρὸ τῶν σεισμῶν συμβαίνουσιν ἐπὶ χρόνον πλείονα, καὶ ὁ ἀὴρ παρὰ τὴν ἑκάστοτε τοῦ ἔτους ὥραν χειμῶνός τε γίνεται καυματωδέστερος καὶ ἐν θέρει μετὰ ἀχλύος μᾶλλον ὁ κύκλος παρέχεται τοῦ ἡλίου τὴν χρόαν παρὰ τὸ εἰωθὸς ἤτοι ἐς τὸ ἐρυθρότερον ἢ καὶ ἡσυχῇ ῥέπουσαν ἐς τὸ μελάντερον·
In general, therefore, when great earthquakes are about to occur—those that surpass others in their magnitude and extend over a very large portion of the world—the god commonly gives warning in ways he most often employs: either continuous rains or droughts occur for a considerable time beforehand, and the atmosphere, according to the particular season of the year, becomes hotter in winter, while in summer the disk of the sun is usually seen dimly through mist, changing its accustomed color either toward red or quietly inclining toward darkness.