“What follows two days of rain in Oregon? Monday!” is a joke that has been told about many geographical locations. ““What comes after two days of rain in Vermont?” was cited in a Vermont newspaper in August 1986.
 
“What comes after two days of rain in Oregon? (Monday)” was cited in December 1986, from an Oregon Ungreeting Card (“ungreeting,” to discourage Californians and others from moving to the state). “What follows two days of rain in Cleveland?” was cited in October 1990. The joke has frequently been told about Seattle, Washington.
 
 
27 August 1986, St. Albans (VT) Messenger, “1986—The year that summer took a vacation” by Christopher Graff, pg. 1, col. 1:
MONTPELIER, Vt. (AP)—Question: What’s green and gray and wet all over?
Answer: Vermont this summer.
Question: What comes after two days of rain in Vermont?
Answer: Monday.
 
7 December 1986, Sacramento (CA) Bee, “Both sides take potshots,” pg. MG1:
Popular jokes, which circulated on Oregon Ungreeting Cards, included: “What comes after two days of rain in Oregon? (Monday),’’ ...
 
7 October 1990, The Plain Dealer (Cleveland, OH), “Soddenly, weekends disappearing” by Brent Larkin, Lake/Geauga sec., pg. 1-B, col. 1:
By now, the joke is becoming a bit old, but no less true. What follows two days of rain in Cleveland?
 
Monday.
 
16 May 1991, Fort Wayne (IN) News Sentinel, “Weather dampens Fort fun,” Entertainment Guide, pg. 1T:
The soggy situation makes Hawfield grimace at that old joke, “What follows two days of rain in Fort Wayne? Monday.”
 
Google Books
A Treasury of Humor:
Thousands of humorous stories, jokes, anecdotes and one-liners, up-to-date and categorized for ease of use
By Lowell D. Streiker
Peabody, MA: Hendrickson
2000
Pg. 425:
Question: What normally follows two days of rain?
Answer: Monday.
—Ron Dentinger
 
Google Books
Insight Guides: Seattle
By Scott Rutherford and Brian Bell
Singapore: APA Publications; Maspeth, NY: Distributed in the U.S. by Langenscheidt Publishers
2003  
Pg. 50:
“What comes after two days of rain?” Monday, of course.
 
KOMO News (Seattle, WA)
2 Days Of Rain In Seattle? Must Be The Weekend Again
By Scott Sistek   Published: Feb 11, 2005 at 2:43 PM PDT Last Updated: Aug 31, 2006 at 1:51 AM PDT
SEATTLE - You know the old joke: What’s two days of rain in Seattle called? A weekend.
   
Linda’s Stellar Stitches
What follows two days of rain in Oregon?
May 29, 2012 by lindasteller
Monday!  Well, or so the joke goes.  Or, we might say, what follows three days of deepest gloom in Oregon?  The Tuesday after a holiday weekend!  And, of course, we all awoke this morning to sunshine.  Yeah!  I don’t care that it’s not the weekend anymore.  Who am I kidding?  I’m retired, right?  I’ll take the sun any time I can get it.