Spring is traditionally the busiest season for home sales, and while this year’s market dynamics have shifted strongly in favor of buyers, broader forces in the economy are creating significant challenges.

The most important factor in any season is mortgage rates. They were expected to be lower this year, as the Federal Reserve dropped its lending rate to counter inflation, but the war with Iran has turned that on its head. The cost of oil is shooting higher, leading to rising inflation and causing the Fed to reconsider.

Now, U.S. interest rates are rising, with mortgage rates following suit.

The average rate on the popular 30-year-fixed mortgage had started this year lower, even briefly dipping below 6% at the end of February, but it rose sharply this week to 6.53% on Friday, the first day of spring, according to Mortgage News Daily. It is now just 18 basis points below where it was a year ago.

Higher rates will weigh on affordability, but other factors have flipped the market in favor of buyers. Homes are sitting on the market longer, sellers are increasingly willing to lower prices and the supply of homes for sale is rising, albeit not as quickly as it should be.