Looking to buy your first home? Good luck: You've got about one week

House-hunters, start your engines. Even as home prices surge to record highs, properties across the U.S. are selling faster than ever, typically getting snatched up after only one week on the market. 

That's the shortest stretch in home-selling history, according to the National Association of Realtors (NAR). Before the pandemic, homes would sit on the market for roughly three weeks before they were sold, according to NAR data. 

"Buyers are moving quickly during the pandemic" in part because there are fewer homes in their area to choose from, Jessica Lautz, the realtor group's vice president of demographics, said in a statement. 

Not surprisingly, the hothouse housing market is good for sellers. The average home price rose 4% during the past three months alone to a record $310,500, according to property data provider Attom Data Solutions.

Indeed, the coronavirus pandemic has led to an ultra-competitive real estate market, housing experts told CBS MoneyWatch. George Ratiu, senior economist for Realtor.com, said several trends are combining to pose challenges for homebuyers. One is simple demographics: Almost 5 million millennials are turning 30 each year, entering the decade of their lives when they're settling down and looking to purchase a home. Meanwhile, historically low mortgage rates have invited many first-time buyers to enter the market.

The pandemic also nudged many people to pull the trigger, especially for properties with home offices and outdoor space. At the same time, some homeowners are reluctant to sell because of the rising cost of finding another place to live and and the widespread lack of inventory.

Most people who are able to quickly snag a house have gone through the homebuying process before, according to NAR. That can leave first-time buyers out in the cold, especially given the soaring cost of rent and heavy student loan debt that can make it hard for many younger Americans to save for a down payment. 

Buying a home costs slightly more than five times what the average American earns in a year, according to Real Estate Witch. The homebuyer education website found that the most affordable major cities for buying a home are Pittsburgh, Cleveland and Oklahoma City. The least affordable are Los Angeles, San Francisco and New York.