“It wasn’t raining when Noah built the Ark” is a proverbial saying that means that one should plan ahead. “It Wasn’t Raining When Noah Commenced the Ark” was cited in print in 1924, when it appeared in a newspaper advertisement telling people to stock up on coal for the winter. Similar ads appeared in many cities in the 1920s and 1930s.
 
The saying is sometimes credited to Howard Ruff (a financial adviser born in 1931), but the saying existed before he was born. The saying is also sometimes credited to Richard Cushing (1895-1970), an American prelate of the Roman Catholic Church, but it’s highly unlikely that he was the first to use it.
 
“The time to fix the roof is when the sun is shining” is a similar proverb.
   
 
Wikipedia: Noah’s Ark
Noah’s Ark (Arabic: سفينة نوح‎; Hebrew: תיבת נח‎; Biblical Hebrew: Tevat Noaḥ) is the vessel in the Genesis flood narrative (Genesis chapters 6–9) by which the Patriarch Noah saves himself, his family, and a remnant of all the world’s animals when God decides to destroy the world because of humanity’s evil deeds. God gives Noah detailed instructions for building the ark: it is to be of gopher wood, smeared inside and out with pitch, with three decks and internal compartments; it will be 300 cubits long, 50 wide, and 30 high; it will have a roof “finished to a cubit upward”, and an entrance on the side.
 
19 June 1924, Emporia (KS) Daily Gazette, pg. 10, col. 7 ad:
It Wasn’t Raining
When Noah Commenced the Ark.
IF WINTER COMES
Will You Be As Well Prepared As Noah?
Better Let Us Fill Your Bin Now.
RICH COAL CO.
 
30 September 1927, Morning Oregonian (Portland, OR), Economy Tips sec., pg. 1, col. 1 ad:
IT WASN’T RAINING WHEN NOAH COMMENCED THE ARK.
When winter comes, will you be as well prepared as Noah?
Why wait? Fill your basement with the kind of coal and wood that will give real comfort during the wintry days.
Edlefsen Fuel Co.
 
Google News Archive
13 October 1930, The Leader-Post (Regina, Saskatchewan), pg. 8, col. 7 ad:
It Wasn’t Raining When Noah Built the Ark.
—and to be sure it isn’t winter now, but why not use Noah’s brand of foresight and fill your coal bin now with one of our high-grade coals, either Sovereign Lump, Sun Lump or Minehead Inferno; also Stove Coal, Lignite Lump, Steam Coal. Good dry Poplar, Spruce, Jackpine, Slabs and Birch Hardwood for fireplaces.
Buy Your Coal Now From
Regina Supply Co., Ltd.
   
Google News Archive
25 November 1930, The Daily News (Ludington, MI), pg. 2, col. 4:
It Wasn’t Raining When Noah Built the Ark.
And, to be sure, it is not zero now. But why not use Noah’s brand of foresight and fill your coal bin now, for col weather is not far off.
GEORGE ABAIR
Always Good Coal
 
OCLC WorldCat record
“It wasn’t raining when Noah built the Ark”.
Edition/Format: Article Article : English
Publication: American Association of Industrial Nurses journal, 1966 Mar; 14(3): 29
Database: From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
 
Google Books
You Can Almost Take It With You:
Commonsense investing and estate planning
By Edwin C. Anderson
Belmont, CA: David S. Lake Publishers
1987
Pg. 67:
It wasn’t raining when Noah built the Ark.
Howard Ruff
 
Google Books
Smart Salespeople Sometimes Wear Plaid:
Dare to be extraordinary in a mediocre world
By Barry Graham Munro
Rocklin, CA : Prima Pub.
1994
Pg. 173:
Always plan ahead, it wasn’t raining when Noah built the ark.
RICHARD CUSHING
   
OCLC WorldCat record
It Wasn’t Raining When Noah Built the Ark
Author: Michele Mary Volesko
Edition/Format: Article Article : English
Publication: Internet Reference Services Quarterly, v6 n3-4 (200109): 99-131
Database: CrossRef
 
OCLC WorldCat record
It wasn’t raining when Noah built the Ark : family preparedness hints
Author: Tami Girsberger
Publisher: Sandy, Utah : Leatherwood Press, ©2008.
Edition/Format:   Book : English