Sea surface temps (even in fairly shallow waters which are open to the open ocean) are mainly affected by the general ocean currents which transport warmer or cooler water into an area, upwelling or mixing of waters of different temps from below, and atmospheric influences (clouds/precip which affect the amount of solar energy hitting the surface, etc).
Because water has a high heat capacity, large bodies of water including coastal waters have very little diurnal variation so there's little temp change between day and night. I hope that answers your question :)


There does appear to be a faint glimmer of hope of a very modest increasing trend with precip potential as we head later into the month (and a period of a more established northeasterly wind flow) as can be seen in the 2nd EC ensemble graphic above where even the driest 10% of its members have of a little bit of precip potential starting within the 7-14 day timeframe from now (the more aggressive scenarios have it starting earlier).... and the latest ACCESS-S output showing a temporary period of close to even odds of drier/wetter than normal conditions sometime between the 23rd and 29th in southern QLD Sep: http://www.bom.gov.au/cl...rainfall/median/weekly/1
(although "even odds" being the operative words here - it doesn't necessarily mean there'll be wet conditions).

There's nothing yet that currently indicates any good confidence of big rain events within the next few weeks but even just a little bit of rainfall from some shower or thunderstorm activity would be nice... even if it means only some locations get wet while others don't.