[hinkley]

If your water source is cooler than ambient air, is that still a problem?

If it works less well on cool days, well you don't need as much water on cool days as you do on hot ones.

[jjk166]

Ambient here is referring to the temperature of the water. The hotter the air is, the higher the partial pressure of water can be, meaning you need to take even more heat out to get it to condense.

[trashtester]

As long as you use the sea water to cool the steam, this is not really an issue. The more energy you extract from the steam, the less additional energy you need to evaporate the water.