Yesterday, I gave you ancient weather predictions based upon the moon I gave fair warning then that today, I would give you Aratos' weather predictions based upon the sun--which are equally fascinating in my opinion. Tomorrow, you can sink your teeth in something a little beefier, but for today, enjoy Aratos' advice from the second half of his excellent Phaenomena.

"To the Sun’s march at East and West give heed. His hints give even more pertinent warning both at setting, and when he comes from below the verge. May not his orb, whenever thou desires a fair day, be variegated when first his arrows strike the earth, and may he wear no mark at all but shine stainless altogether. If again thus all pure he be in the hour when the oxen are loosed, and set cloudless in the evening with gentle beam, he will still be at the coming dawn attended with fair weather. But not so, when he rises with seemingly hollow disk, nor when his beams part to strike or North or South, while his center is bright. But then in truth he journeys either through rain or through wind.
Scan closely, if his beams allow thee, the Sun himself, for scanning him is best, to see if either some blush run over him, as often he shows a blush or here or there, when he fares through trailing clouds, or if haply he is darkened. Let the dark stain be sign to thee of coming rain, and every blush be sign of wind. But if he is draped both black and red at once, he will bring rain and will strain beneath the wind. But if the rays of the rising or setting Sun converge and crowd on one spot, or if he go from night to dawn, or from dawn to night, closely beset with clouds, those days will run in company with rushing rain. Nor be thou heedless of rain, what time before him rises a thin mist, after which the Sun himself ascends with scanty beams. But when a broad belt of mist seems to melt and widen before the rising Sun and anon narrows to less, fair will be his course, and fair too, if in the season of winter his hue wax wan at eventide. But for tomorrow’s rain face the setting Sun and scan the clouds. If a darkening cloud the beams that wheel between the Sun and it part to either side of the cloud, thou shalt still need shelter for the dawn. But if without a cloud he dip in the western ocean, and as he is sinking, or still when he is gone, the clouds stand near him blushing red, neither on the morrow nor in the night needst thou be over-fearful of rain. But fear the coming rain when on a sudden the Sun’s rays seem to thin and pale – just as they often fade when the Moon overshadows them, what time she stands straight between the earth and Sun; nor are the fields unwetted on that day, when before the dawn, as the Sun delays to shine, reddish clouds appear here or there. Be not heedless either of wind or rain to come, when, while the Sun is still below the verge, his precursor beams shine shadowy in the dawn. The more those beams are borne in shadow, the surer the sign they give of rain, but if but faint the dusk that veils his beams, like a soft mist of vapor, that veil of dusk portends wind. Nor are dark halos near the Sun signs of fair weather: when nearer the Sun and dark without relief, they portend greater storms: if there are two rings, they will herald tempests fiercer still.
Marks as the Sun is rising or setting, whether the clouds, called parhelia, blush (on South or North or both), nor make the observation in careless mood. For when on both sides at once those clouds gird the Sun, low down upon the horizon, there is no lingering of the storm that comes from Zeus. But if only one shine purple to the North, form the North will it bring the blast; if in the South, from the South; or down pour the pattering raindrops.
With even greater care mark those signals when in the West, for from the West the warnings are given ever with equal and unfailing certainty." [819 - 890]