Depositors jammed the offices of banks and savings institutions in record numbers yesterday to snap up the much-ballyhooed All Savers certificates, prompting many institutions to extend weekend hours to meet heavy denand.

While opening-day sales of the new tax-exempt certificates were described as brisk but modest Thursday, banks and thrift institutions yesterday reported record volumes of new deposits as customers queued up, many of them forming long lines before the start of normal business hours.

Washington Federal Savings and Loan Association will keep its main office on Wisconsin Avenue and its Chevy Chase office open until midnight.

Several other local institutions will be open today until at least 1 p.m. Dominion Federal Savings and Loan Association plans to keep its offices open until 3 p.m., but "as long as somebody wants to open an account we'll stay open," said George Cain, president of the savings department.

Cain said Dominion Federal received $3 million in All Savers accounts Thursday and had added 1,000 new accounts by midday yesterday.

"If we keep going like this, we could exceed $10 million" in All Savers accounts "in one day," Washington Federal's president, James L. Harris, said at the height of business yesterday.

Sales of All Savers yesterday were up 50 percent from Thursday's total at D.C. National Bank, said Robert Pincus, the bank's senior vice president.

After visiting several of his association's branches, Jim Haynes, a vice president at Government Services Savings and Loan Inc. of Bethesda, declared: "It's a logjam in every one."

Industry officials said the story was much the same across the nation.

They noted that the rush to buy the certificates yesterday was expected after the results of Thursday's one-year Treasury bill auction were made public.

Interest on the All Savers, based on Thursday's auction, will be 12.14 percent, starting Monday. The interest based on the previous auction last month and in effect until tonight, is 12.61 percent.

With that in mind, depositors flocked to banks, S&Ls and credit unions yesterday to take advantage of the higher rate, which they were able to lock in for a year.

Interest on the certificates is exempt from federal income taxes up to $1,000 for single taxpayers and $2,000 for joint returns. Maryland and Virginia have established the same exemption but interest earned in the District will be taxable.

The race to buy the certificates this weekend "is meeting and beating our expectations," said a spokesman for the U.S. League of Savings Associations. On Thursday, "A lot of people were asking questions. Today, a lot of those same people are back buying certificates," said the league's spokesman.

League officials had estimated that $250 billion to $300 billion would be invested in the All Savers by the end of 1982, when they expire. They further estimated that $125 billion to $130 billion of that would go to S&Ls.

Although it's still too early to tell what total sales have been in the first two days, the league estimates 25 percent to 30 percent can be attributed to new funds rather than transfers from existing accounts.

Several local banking and thrift officials said a large portion of money invested in All Savers yesterday had been transferred from passbook or other accounts. Many said some investors had withdrawn money from money market mutual funds to buy All Savers certificates.

Yields on money market mutual funds have been much higher but are taxable.

"We know that people are taking money from money market funds and checking and savings accounts, but a lot of it is new money," said John Miller, executive vice president at Citizens Bank of Maryland.

Whatever the source, money flowed into the new accounts at unprecedented rates, many officials reported.

The Navy Federal Credit Union, purported to be the largest in the nation, sold about $1.5 million in All Savers certificates Thursday and expected to surpass that yesterday, said an official.

Lines formed as early as eight o'clock yesterday at Chicago Federal Savings and Loan Association.

At Far West Federal Savings and Loan Association in Portland, Ore., long lines of depositors greeted employes arriving early yesterday at all 40 offices.