Climate and Seasons
Israel has a Mediterranean climate with long, hot, rainless summers and relatively short, cool, rainy winters see wikipedia
The harvests were so important to their culture that Biblical events were reckoned according to the harvests (Gen 30:14; Josh 3:15; Judges 15:1; Ruth 1:22; 2:23; 1Sam 6:13; 2Sam 21:9; 23:13).
The Three Harvests
The harvest cycle starts with the early rain, in the fall after completion of last year's harvest and is just in time to do the planting. The latter rain occurs just before the spring harvest and makes the grain plump and full. Following the latter rain, there are three distinct harvests at three separate times, to complete the annual harvest cycle. First the barley, a little while later, the wheat, and finally, the grapes. These three harvests correspond with three major Jewish feasts (see The Three Feasts) (Exodus 23:16; 34:21,22). Spiritual and cultural life revolved around the harvests and their related Holy Days / feasts. Each holds spiritual significance that will better clarify the simile to Yahweh's final harvests and His Plan of Redemption.
Three times thou shalt keep a feast unto me in the year. Thou shalt keep the [1] feast of unleavened bread: (thou shalt eat unleavened bread seven days, as I commanded thee, in the time appointed of the month Abib; for in it thou camest out from Egypt: and none shall appear before me empty:) And the [2] feast of harvest, the firstfruits of thy labours, which thou hast sown in the field: and the [3] feast of ingathering, which is in the end of the year, when thou hast gathered in thy labours out of the field. Three times in the year all thy males shall appear before the Yahweh Elohim. Exodus 23:14-17
Three times in a year shall all thy males appear before Yahweh thy Elohim in the place which he shall choose; in the [1] feast of unleavened bread, and in the [2] feast of weeks, and in the [3] feast of tabernacles: and they shall not appear before Yahweh empty: [note, these are different names for the same feasts] Deuteronomy 16:16
Modern Israel has diluted and altered Yahweh's Word by making seven feasts. Some of these extra feasts are actually part of Yahweh's three and a few (Purim and Chanukah) are new, but NOT requiring appearance of the males before Yahweh.
Many Christians have completely abolished Yahweh's three feasts by "nailing them to the cross", but without any direct instruction from Yahweh. Yahweh's feasts are as relevant today as they were before the cross. The sacrifice of the lamb is no longer necessary because Yahushua (Jesus) accomplished that, but the feasts still celebrate the harvests, which have continued after the cross and look forward to Yahweh's final harvests when He restores His creation.
Yahweh's Feasts (see The Feasts of Redemption for a more thorough study)
(1) The feast of unleavened bread is part of the Passover at the time of the barley harvest (compare Ruth 1:22). This is usually in April according to Roman time.
(2) The feast of harvest or feast of weeks contains Pentecost (7 weeks plus 50 days later) at the wheat harvest (Exodus 34:22), and
(3) The feast of ingathering or feast of tabernacles contains the Day of Atonement at the end of the year (October according to Roman time) during the grape harvest.
The seasons have not changed since Bible times. Between the reaping of the barley in April and the wheat in July, most of the other cereals are reaped. The grapes begin to ripen in August, but the gathering in for making wine and molasses, and the storing of the dried figs and raisins, is at the end of September. Between the barley harvest in April and the wheat harvest, only a few showers fall, which are welcomed because they increase the yield of wheat (compare Amos 4:7). Samuel made use of the unusual occurrence of rain during the wheat harvest to strike fear into the hearts of the people (1Sa 12:17). Such an unusual storm of excessive violence visited Syria in 1912, and did much damage to the harvests, bringing fear to the superstitious farmers, who thought some greater disaster awaited them. From the wheat harvest until the fruit harvest no rain falls (2Sa 21:10; Jer 5:24; compare Prov 26:1). The harvesters long for cool weather during the reaping season (compare Prov 25:13).
Sheep don't play a direct role in the harvest cycle, but they certainly played a large part in the sacrificial system and comparisons of His people to sheep. (see here for an overview of some of these comparisons)
