What would be causing my Neon to overheat?

What is your question?

Neon over heats after driving for about 25 miles in weather over 40° F. Under 40°F it drives fine. No leaks, both fans kick on, recently replaced thermostat. Engine coolant level is good, but levels never seems to change even if the car is under pressure. Any tips are very much appreciated

What makes this problem better or worse?

Colder weather it runs fine. Over 40°F it overheats

How long has your 2005 Dodge Neon had this problem?

Few months since I've bought the car. Ran good during Wisconsin winter