Key Biscayne, FL vs St. Augustine South, FL

The cost of living difference between Key Biscayne, FL and St. Augustine South, FL is dramatic. St. Augustine South is 135% cheaper than Key Biscayne, a gap that translates to thousands of dollars per year in household expenses. Key Biscayne has a cost index of 247 while St. Augustine South sits at 105, making this one of the more striking comparisons on our site. Relocating between these cities would require a serious reassessment of budget and lifestyle expectations.

On the housing front, median rent in Key Biscayne is $3,501/month compared to $1,452/month in St. Augustine South — a 141% difference. Home values follow the same pattern: St. Augustine South is more affordable at $319,200 median vs $1,238,700.

Median household income in Key Biscayne is $172,604 compared to $74,873 in St. Augustine South (+130.5%). The higher salaries in Key Biscayne partially offset the cost difference, but don't fully close the gap. Looking at affordability, residents of Key Biscayne spend roughly 24.3% of their income on rent, more than the 23.3% in St. Augustine South.

Climate-wise, Key Biscayne is notably warmer with an average of 77.4°F compared to 71.4°F in St. Augustine South. Key Biscayne receives more rainfall at 51" per year compared to 47.6" in St. Augustine South.