Why is RIchmond so much colder in winter than similar inland areas near Sydney?

Question

why is RIchmond so much colder in winter than similar inland areas near Sydney? An example is Campbelltown and Liverpool which are simialr distances from the Ocean but yet Richmond regularly has lower temperatures 3 degrees below these places

Answer 1

Mr. Freeze lives there.

Answer 2

Is it further south, or is it at a higher attitude?

Answer 3

Perhaps Campbelltown and Liverpool are more influenced by the moderation effects of the ocean...  or maybe the Heat Island Effect is keeping temps warmer in the suburbs closer to Sydney.  Would you consider Richmond further out in the country than the other 2 towns?  Generally, interior portions of cities remain slightly warmer than the outlier towns around them.  

Also, consider possibly a slight adjustment if the elevation is a bit higher than that of those two cities.