The Feast of Trumpets is known Rosh Hashanah (head of the year) by the Jews because the feast day starts the Jewish New Year.  It is also known by the Jews as Yom Teruah (a day of shouting/blasting). 

The date for the Feast of Trumpets is the first day of the seventh month.

Lev 23:24  “Speak to the children of Israel, saying: ‘In the seventh month, on the first day of the month, you shall have a sabbath-rest, a memorial of blowing of trumpets, a holy convocation.
Lev 23:25  You shall do no customary work on it; and you shall offer an offering made by fire to the LORD.’ “

It is a Sabbath day, that is a day of rest where no customary work is done.  The Feast of Trumpets is mentioned again in Numbers where more detail is given regarding the offerings to be made.

Num 29:1  ‘And in the seventh month, on the first day of the month, you shall have a holy convocation. You shall do no customary work. For you it is a day of blowing the trumpets.

There is nothing more in the Bible directly relating to the Feast of Trumpets.  However, various indirect references reveal the meaning of this Feast.

In attempting to answer the question, “What is the meaning of the Feast of Trumpets?”, it’s helpful to consider what trumpets were used for. 

Use of Trumpets

There are three main purposes of trumpets mentioned in the Bible.

1) Trumpets were used for gathering people.

Num 10:2  “Make two silver trumpets for yourself; you shall make them of hammered work; you shall use them for calling the congregation and for directing the movement of the camps.
Num 10:3  When they blow both of them, all the congregation shall gather before you at the door of the tabernacle of meeting.

2) Trumpets were used for sounding an alarm when going to war.

Num 10:9  “When you go to war in your land against the enemy who oppresses you, then you shall sound an alarm with the trumpets, and you will be remembered before the LORD your God, and you will be saved from your enemies.

An example of trumpets being used during war is Joshua and the battle of Jericho; at the blast of trumpets the walls fell down.  Another is Gideon and the defeat of the Midianites; at the blast of trumpets God caused the Midianites to turn on each other.

3) Trumpets were used on the Feast days and the beginning of months when offerings were made.

Num 10:10  Also in the day of your gladness, in your appointed feasts, and at the beginning of your months, you shall blow the trumpets over your burnt offerings and over the sacrifices of your peace offerings; and they shall be a memorial for you before your God: I am the LORD your God.”

What Trumpets are Associated with

Trumpets are also associated with the day of the Lord.

Joe 2:1  Blow the trumpet in Zion, And sound an alarm in My holy mountain! Let all the inhabitants of the land tremble; For the day of the LORD is coming, For it is at hand:

Zep 1:14  The great day of the LORD is near; It is near and hastens quickly. The noise of the day of the LORD is bitter; There the mighty men shall cry out.
Zep 1:15  That day is a day of wrath, A day of trouble and distress, A day of devastation and desolation, A day of darkness and gloominess, A day of clouds and thick darkness,
Zep 1:16  A day of trumpet and alarm Against the fortified cities And against the high towers.

A trumpet (a single trumpet) is associated with the resurrection of the saints.

1Co 15:52  in a moment, in the twinkling of an eye, at the last trumpet. For the trumpet will sound, and the dead will be raised incorruptible, and we shall be changed.

1Th 4:16  For the Lord Himself will descend from heaven with a shout, with the voice of an archangel, and with the trumpet of God. And the dead in Christ will rise first.
1Th 4:17  Then we who are alive and remain shall be caught up together with them in the clouds to meet the Lord in the air. And thus we shall always be with the Lord.

And finally there are the seven trumpets of Revelation, with the seven angels who blow them.

Rev 8:2  And I saw the seven angels who stand before God, and to them were given seven trumpets.

The first 4 trumpets are found in Revelation 8, the 5^th and 6^th in Revelation 9, and the 7^th in Revelation 11.

Rev 11:15  Then the seventh angel sounded: And there were loud voices in heaven, saying, “The kingdoms of this world have become the kingdoms of our Lord and of His Christ, and He shall reign forever and ever!”

The Explanation

How are these all tied together?  The simplest and most obvious explanation is that the Feast of Trumpets portrays the seven trumpets of Revelation which describe the terrible events of the Day of the Lord. 

The Day of the Lord is clearly not one day (24 hours) as too many things happen on the seven trumpet blasts.  Using the Numbers 14:34 and Ezekiel 4:5-6 as an example of how God has used “a day” for “a year” we can make an educated guess that the Day of the Lord lasts about a year. 

Num 14:34  According to the number of the days in which you spied out the land, forty days, for each day you shall bear your guilt one year, namely forty years, and you shall know My rejection.

Eze 4:5  For I have laid on you the years of their iniquity, according to the number of the days, three hundred and ninety days; so you shall bear the iniquity of the house of Israel.
Eze 4:6  And when you have completed them, lie again on your right side; then you shall bear the iniquity of the house of Judah forty days. I have laid on you a day for each year.

The last trumpet referred to in 1 Corinthians 15:52 is surely a reference to the 7^th trumpet of Revelation where “The kingdoms of this world have become the kingdoms of our Lord and of His Christ”.

Here is some interesting speculation.  Perhaps the first trumpet is blown on the Feast of Trumpets.  About 9 months later, on the Feast of Pentecost, the 7^th trumpet is blown (see “What is the meaning of the Feast of Pentecost?”).  The resurrected saints rise to meet Jesus Christ in the clouds where they stay for about 3 months until the following Feast of Trumpets, which is the completion of the Day of the Lord, at which point they touch down on the earth with Jesus Christ and rule for 1000 years.

Conclusion

The Feast of Trumpets portrays the seven trumpets of Revelation which describe the terrible events of the Day of the Lord.