Not sure I understand 'TO HAVE THOSE TEEEMPS'?
There is a point of diminishing returns on watercooling and you cannot cool below ambient room temp. Your delta-T can approach < 1C but it cannot drop below it...aka, water temp cannot ever be lower than room temperature, not below 1C or 0C. Delta-T is the difference of the coolant/water temp vs. room temperature.
So, if your ambient room temperature is hotter, your delta-T is still a function of the ambient room temp vs. the loop cooling potential. The reported temps you will see in RealTemp or CoreTemp will still be warmer as the room temperature rises. It will also fall as room temp gets lower.
This is no different than normal air cooling - water cooling is just more efficient in absorbing thermal load and holding it than air, but it still means you are dependent upon air cooling (air blown through radiators via fans) in order to transfer that energy into the ambient air.