Paint suddenly cracked on outside doors - extreme weather to blame?

[d000hg]

Now we all know how easy it is to spot a crack that's been there for years and then you can't stop seeing it, but the other week I noticed cracks on my front door and especially on the back door to my garage. Both had the same paint on, don't know from when but looks fairy good. Or looked... on the garage door there are several cracks (down ever joint maybe), Quite deep looking.

Is it feasible the several weeks of sun caused this to happen so quickly? Does gloss paint suddenly 'go' once it gets a bit brittle?

I assume it just needs repainting (good chance to change the colour) but I was curious because at first glance my thought was "what the heck happened to my doors"!

 

[opps]

The dry weather may have caused the timber to dry and contract. It will be particularly noticeable where recessed panels meet the rails and styles.

Rather than using caulk, I would recommend using a MS polymer (eg CT1). It will allow for a greater degree of movement than caulk. They do cost more and need to be spot primed with water based paint.

Small cracks where the rails meet the styles- you can use an epoxy resin filler (eg Timbabuild or RepairCare) but they are expensive. Consider a soft filler such as Toupret Redlite or Red devil OneTime.

If the doors are mortice and tennon rather than dowelled, you can drill and glue dowels through the joints to prevent them moving. In an ideal world you would reglue the joins and clamp them shut but I doubt you have clamps long enough.