John Wesley on Joshua 3:15

All the time of harvest - This is meant not of wheat - harvest, but of the barley - harvest, as is manifest from their keeping the passover at their first entrance, Jos 5:10, which was kept on the fourteenth day of the first month, when they were to bring a sheaf of their first - fruits, which were of barley. So that this harvest in those hot countries fell very early in the spring, when rivers used to swell most; partly because of the rains which have fallen all the winter, partly because of the snows which melt and come into the rivers. And this time God chose that the miracle might be more glorious, more amazing and terrible to the Canaanites; and that the Israelites might be entertained at their first entrance with plentiful and comfortable provisions.