Matthew Poole and continuators on Joshua 3:15

15 And as they that bare the ark were come unto Jordan, and the feet of the priests that bare the ark were dipped in the brim of the water, (for Jordan overfloweth all his banks all the time of harvest)

Which is also noted, 1 Chron. 12. 15. Ecclus. 24. 36. and by Aristoeas in his History of the LXX Interpreters. This is meant not of the Wheat-harvest, but of the Barleyharvest, (which was before it, Ruth 1. 22. 2 Sam. 21. 9.) as is manifest from their keeping of the Passover at their first entrance, Iosh. 5. 10. which Feast was kept on the fourteenth day of their first Month, when they were to bring a Sheaf of their first-fruits, Levit. 23. 10. Deut. 16. 9, 10. which were of Barley, as Iosephus affirms, and is evident from the thing it self. So that this Harvest in those hot Countreys fell very early in the Spring, when Rivers use to swell most; partly because of the rains which have fallen all the Winter, and partly because of the Snows which then melt into Water and come into the Rivers; for which Reasons the same overflowing of Water which is here ascribed to Iordan, is by other Authors ascribed to Euphrates, and Tigris, and the Rhine, and Main, &c. And this time God chose for this Work, partly that the Miracle might be more glorious in it self, more obliging to the Israelites, and more amazing and terrible to the Canaanites; and partly that the Israelites might be entertained at their first entrance with more plentiful and comfortable Provisions.

Marginal references: 1 Chron. 12. 15. Jer. 12. 5. & 49. 19.