Hey, you want spring? You came to the wrong place.

Out of 20 days in April it has rained on 15.

Out of 20 days in April it has been colder than normal on 15. On 10 of those it also rained.

You know how many days this month have been neither wet nor cold?

One. Easter Monday. Sun came out and everything.

Remember that. It may be all the spring you get.

The last five days have averaged 15 degrees below normal. Yesterday's average temperature was 44.

So what does all this mean, and will we all go crazy?

Probably not, says Dr. Alan Levenson, the American Psychiatric Association's designated hitter on weather topics.

Weather, he says, is "a general determinant of human behavior, not a specific one."

Levenson, who practices in Tucson but hails from Boston and thus knows about endless cold, says prolonged bad weather may aggravate existing anxiety, but will probably not make any normal person, say, take an ax to his mother.

The problem, in any case, is not rain or temperature, he says, but "any period of prolonged waiting" for something cyclical like spring.

"We all have a sense, accurate or not, of how long we should have to wait for something. When that period is prolonged, we get uncomfortable with the apparent uncertainty, and start to wonder if it ever will end."

Exactly.

"But it's mostly a matter of perception," Levenson says. "You're talking about a rainy April. April is supposed to be a rainy month. It just seems worse because of the cold."

Even the cold, the weather service says, while way off normal on the average, has not broken a single low temperature record this month.

Other areas around the country have been less fortunate. The third day of record-breaking cold swept a dozen cities in the East from Muskegon, Mich., to Miami Beach yesterday. It was 30 degees in Atlanta, 26 in Nashville and 31 in Charleston, S.C.

An intense low pressure over Long Island Sound was moving slowly northeastward, trailing April snow over the eastern mountains and gale winds and 10-foot seas along the Atlantic Coast.

Fifteen inches of snow fell on the mountain community of Tobyhanna, Pa., and eight inches in some suburbs of Philadelphia. Snow depths elsewhere ranged up to 18 inches in the Catskill Mountains of New York and up to 16 in northern New Jersey.

President Reagan, meanwhile, declared major disasters yesterday in 11 southeast Louisiana parishes devastated by spring flooding earlier in the month. Total damages from the flooding in southeast Louisiana have been estimated at $425 million. At least 367 homes were destroyed.

This week's cold temperatures devastated fruit crops in much of the Deep South. Those in the Shenandoah Valley, most vulnerable of the Washington region's crops to late frost, suffered some damage from temperatures in the 20s Sunday and Tuesday nights, but probably not enough to reduce crops.

Dr. Calvin Lyons, extension horticulturist at Virginia Tech's Fruit Research Laboratory in Winchester, said the prolonged cold had put both apple and peach trees about a week behind schedule in blooming.

Normally, he said, peach trees would have reached full bloom April 15. In that stage, Tuesday night's 24-degree temperatures in some orchards in the Blue Ridge foothills would have killed 90 percent of the potential fruit. In their existing state, probably 10 percent or less of the blossoms died, Lyons said, well within the number that would normally be thinned out as a matter of course.

People are doing even better than fruit trees. Calls to a half dozen clinics and health maintenance organizations in Washington yielded opinions that the area is showing no significant increase in colds or flu complaints over those logged in a normal April.