Washington's average APR for a 30-year mortgage recently decreased slightly to 6.699%, showing a downward trend over the past three months. The average APR for a 30-year fixed refinance mortgage also fell to 6.752%. Mortgage rates fluctuate due to economic factors like Treasury yields, inflation, and Federal Reserve policies. Securing the best rates involves researching current trends, comparing lenders, maintaining a strong credit score, and making a substantial down payment.