When Bob Asmann, executive vice president of the Fourth National Bank & Trust Co. in Wichita, Kan., looked out the window at 7 a.m. on a cold wet morning last Saturday, he saw 500 or 600 people standing in line. They were waiting for a chance to open Individual Retirement Accounts.

The bank's customers were lured by an advertisement offering 18 percent interest for 15 years on an initial deposit of $2,000. (The interest on the deposit and subsequent contributions go into a variable rate fund based on 90-day Treasury bill rates.) Others had telephoned for information from as far away as Hawaii and Alaska.

By the end of the day, the bank's 130 employes had opened 3,000 accounts, adding $6 million to its coffers.

Asmann called the reaction "unbelievable." Nevertheless he said the bank has decided to end the promotional offer after the first 5,000 accounts are signed up, probably today.

In Cedar Rapids, Iowa, Merchants National Bank offered to pay 50 percent for the first quarter to anyone who opened a variable rate IRA. A 12-inch snowfall on the first day of sale kept the crowds away from the door, but not off the phone, according to Vice President Cal Coquillette.

He reported establishing almost 300 accounts by phone on Saturday. Due to the demand, Merchants has decided to cease taking out-of-town accounts Thursday.

Nothing similar seems to have occurred in the Washington area. The lines visible at some tellers' windows yesterday were made up not of IRA purchasers but of people replenishing their cash supplies after the holidays, according to local bankers. They definitely were not a repeat of the lines that formed on the first day All Savers certificates went on sale in October.

Reports from a half dozen banks and savings and loans indicate sales volume of IRAs was negligible to moderate on the first weekday in the New Year. Although few people were ready to put up their dollars, however, many were on the telephone asking questions.

At First Maryland Savings and Loan, which is offering a 30 percent annual rate for the first month, sales were slow yesterday; about 20 accounts opened at its three branches.

Washington Federal Savings and Loan stayed open until midnight on the first day All Savers certificates were issued. It opened just 30 IRAs yesterday, but sent out 400 applications. Sixty percent of the savers put in the full amount authorized by law. Washington Federal was paying 13.45 percent on its 18-month, fixed-rate certificate, and 13.39 percent on its variable.

At National Permanent Savings and Loan, about 100 accounts were opened yesterday. Most savers elected to put in the maximum, tax-exempt $2,000, according to Jeff Baxter of the marketing department. Three out of five opted for the fixed rate certificate, paying 13.45 percent. The S&L's variable pays 13 percent.

"IRA is more complicated than All Savers," Baxter explained. "Moreover, financial planners are advising people to wait and shop around." There is no pressure to set up an IRA in the first month before rates go down as there was with the All Savers certificate.

Contributions can be made up until one's 1982 income tax is filed. "I'm glad the public is not being panicked into it," said John Sims, vice president for retirement plans at Continental Federal Savings and Loan. "There are so many options to consider."

First American Bank of Virginia, which was offering an 18-month variable account at 11.69 and a 30-month fixed rate at 12 percent, opened about 100 accounts yesterday. A quarter of the depositors chose to invest the full amount.

At National Bank of Washington, sales were moderate yesterday, meaning that while hundreds were shopping, only dozens were buying. Of those who did buy, many put in less than $2,000 and chose the floating rate certificate, a spokeswoman said. Yesterday's 18-month fixed rate at NBW was 14 percent; its 18-month variable, 12 1/2 percent; its 2 1/2-year variable, 13.45 percent; its 4-year fixed rate, 12 percent.