what Joel spoke of was a period during which the Holy Spirit would be outpoured. Peter was saying this is the beginning. These outpourings would end with what is called "the day of the Lord" which is the day of the Lord's return. Joel speaks of this event frequently and it is central to his whole prophetic message (1:15; 2:1-2, 11, 31; 3:14, 18). It is a day of wrath and judgement for sinners but a day of salvation and reward for the righteous.
It is in the context of this day and prior to it that he speaks of the outpouring of the Spirit which would begin to be fulfilled at Pentecost. Joel exhorts God's people to repentance, prayer and fasting as the pathway to these outpourings. What we see at Pentecost is a taste of the type, manner and power of the outpouring of the Holy Spirit which would be granted to God's people throughout the church age.
Joel along with many other Old Testament prophets spoke of such outpourings. Throughout the OT these outpourings are likened to the coming of rain. When the Lord speaks of His coming to His people in revival in order that a great harvest of souls may be brought in He often typifies it by the former and latter rain (Deut.11:14; Job 29:23; Prov.16:15; Jer.3:3; 5:24; Hos.6:3; Joel 2:23; Zech.10:1; Jm.5:7). This cannot be more clearly stated than by Hosea: "...he shall come unto us as the rain, as the latter and former rain unto the earth."
In Joel in connection with the prophecy concerning the revival which would later begin at Pentecost Joel says: "for he hath given you the former rain moderately, and he will cause to come down for you the rain, the former rain, and the latter rain in the first month."
If we look for a moment at Israel's rainy season we shall understand better what the Lord was saying. Rain fell in two seasons.
1. "the Former rain" (first) Autumn rain. In national Israel the rainy season begins about September time. The period from September to December is called "the former rain" although the main rainfall is usually in October and November. The husbanbman (farmer) watches for the first sign of coming rain so as to be sure the seed is well planted in the ground. It begings gently but turns into heavy rain which prepares the ground and makes the seed to take root and germanate. As a result of the former rain a harvest grows up.
2. "the latter rain" (last) Spring rain. The rainy season finishes with a "latter rain" beginning in February through till April which is granted by God in order to ripen the harvest which began with the former rain. This last rain is the final preparation before harvesting. It is vital to the whole process of harvest and to complete the work begun in the former rain. Both are necessary for a full healthy harvest.
The harvest at its beginning and again at its end was marked by a deluge of rain. But between these two vital points the rain never totally ceased. Between December and February it rained lightly at intervals.
When the OT prophets spoke of the Lord coming to them as the former and latter rains it was filled with meaning. The early Church fully understand the same meaning from the same Scriptures. Seed time and harvest depended upon rain. Both naturally and spiritually the sowing of seed and the reaping of harvest needed the rain.
For the New Testament Church the first rain and first harvest and ingathering came on the day of Pentecost. This was the "former rain" which prepared the ground and brought forth the initial harvest. This heavy rain continued throughout the first century. Since then there have been showers at intervals. Beginning in the 16th century with the Reformation the showers have got stronger as we have moved towards the final harvest. This latter deluge gave us the 18th century Methodist revival, the 1859 revival, the 1904 revival and the Pentecostal revival. The two great periods of revival have been in the early church and again in recent centuries.
But Joel seems to say a strange thing. After talking of the first rain he goes on to say that the Lord will cause to come down: "the former rain, and the latter rain in the first month." The first month was Nisan which is our March/April time. This is at the very end of the raining cycle on the eve of harvest. Joel does not just say that the latter rain will come then the harvest, but states that the latter rain will come then 'the former and latter rain' will be given together at this time just before the harvest. Joel certainly was not talking of the natural cycle. This was a spiritual promise. Does this mean that the end of the Church age will recieve not only the former rain but the latter rain together in the same month? Is this prophecy showing us that we will see the Pentecostal revival of the 1st century as well as the latter rain seen in recent centuries suddenly come together in one last revival?
Before the day of the Lord, the day of Christ's return, we are promised latter rain in order to bring in the last harvest. This revival comes in one month in order to bring in one great last harvest just before the judgement of God falls upon the world when He will pour out His wrath in an unparalled way. Would it seem strange that He sends the greatest revival just before the greatest judgement the world has ever known?