No rainbow will appear for 1 year before the Second Coming
Many members let out a sigh of relief ever time they see a rainbow- but should they? The claim many members make that no rainbows will appear on the earth for one year before the Second Coming of Jesus Christ is based on quotes from the prophet Joseph Smith.
Teachings of the Prophet Joseph Smith, Section Six 1843-44, p.305
The Lord deals with this people as a tender parent with a child, communicating light and intelligence and the knowledge of his ways as they can bear it. The inhabitants of the earth are asleep; they know not the day of their visitation. The Lord hath set the bow in the cloud for a sign that while it shall be seen, seed time and harvest, summer and winter shall not fail; but when it shall disappear woe to that generation, for behold the end cometh quickly.
Teachings of the Prophet Joseph Smith, Section Six 1843-44, p.340
I have asked of the Lord concerning His coming; and while asking the Lord, He gave a sign and said, "In the days of Noah I set a bow in the heavens as a sign and token that in any year that the bow should be seen the Lord would not come; but there should be seed time and harvest during that year: but whenever you see the bow withdrawn, it shall be a token that there shall be famine, pestilence, and great distress among the nations, and that the coming of the Messiah is not far distant.
Teachings of the Prophet Joseph Smith, Section Six 1843-44, p.341
But I will take the responsibility upon myself to prophesy in the name of the Lord, that Christ will not come this year, as Father Miller has prophesied, for we have seen the bow; and I also prophesy, in the name of the Lord, that Christ will not come in forty years; and if God ever spoke by my mouth, He will not come in that length of time. Brethren, when you go home, write it down, that it may be remembered.
From the above quotes from Joseph Smith, it would appear that this is a true myth. The reason it is marked "undetermined" is because we do not know if Smith’s comments were to be taken literally or more figuratively. It has been speculated by members that there are many ways in which a rainbow could not appear: God could change the laws of refraction (he created the world after all), a severe drought could cause no rainbows, or perhaps our eyes will be focused on worldly things and we will just not notice the rainbows. Many members look at these comments more figuratively and don’t believe that every time they see a rainbow, they have another year to prepare for His coming. Why, because no man knows the day or hour...