Tony Filice, Director of Kelvin Francis estate agency, says Brexit could be a key factor.
New figures from Rightmove show that since 2000, some areas of Cardiff have experienced house price rises of over 200%. In parts of Cardiff, some homes are worth £300,000 more than they were twenty years ago.
Other places outside of the city but within the CF postcode such as Merthyr Tydfil, Cowbridge and Bridgend have also experienced house price increases of more than 200%.
Even areas which have seen the lowest rise in housing prices have witnessed great change. Maesteg has experienced the lowest increase of all in the CF postcode area, but house prices here have still risen by 93.70%.
Tony Filice says many factors have resulted in such dramatic rises. But he also says prices are not guaranteed to decrease anytime soon.
Mr Filice says the next three months are critical to the housing market because Brexit potentially has the power to increase nervousness and demand which could then lead prices to swell even more.
Mr Filice also says the removal Severn bridge toll could make a difference. The toll is due to come to an end this weekend, which means cars will no longer have to pay £5.60 to use the bridge. It is thought this will encourage people who currently live and work over the border to move to Cardiff where house prices are cheaper. This will then help drive up housing prices in the Welsh capital.