In the nine-county Bay Area, 8,461 homes were sold last month -- a 22.9 percent increase from the same time last year, according to a report by the real estate information service DataQuick.
The average figure for July, based on data recorded since 1988, is 9,371 home sales.
The median price for a new home or condo was $421,000, which is a 1 percent increase from $417,000 in June and a 12.6 percent jump from July 2011.
July's median price was the highest recorded since it was $447,000 in August 2008.
The increase appears to be connected to a higher share of sales in the mid-to-upper price ranges, according to DataQuick.
Median sale prices in San Francisco, Alameda, Contra Costa, Santa Clara, Solano, Marin, Napa, San Mateo and Sonoma counties all increased in the past year with Napa County seeing the biggest price increase at a 32.6 percent jump.
Median prices in that county were at $281,000 in July 2011 and reached $372,500 this July, according to DataQuick.
The highest home prices in the region this summer are in San Francisco with $714,000 listed as the median cost, while the lowest can be found in Solano County at $188,000.