6.71% marked the average top-tier 30-year fixed mortgage rate on Monday, up from 6.63% on Friday and moving back toward last week's 11-month highs.
Bond-market weakness drove the increase, with many lenders repricing higher in the middle of the day as renewed fighting in Iran lifted fuel-price pressure.
Friday had briefly offered relief, with rates ending just below the prior Friday after touching those 11-month highs earlier last week.
Refinance rates also edged up to 6.635% on July 20, extending a broader July rise tied to the apparent collapse of the U.S.-Iran ceasefire.