Damp around Upvc front door

[rcarp98]

Hi all around the inside of my upvc front door the paint has turned darker. I assume this is damp. Pictures are below. What could be causing this ?

 

[Mr Chibs]

Can you take some pics of the outside please... when it's light

 

[rcarp98]

 

[Ihavenojob]

Possible reaction between the silicone and the plaster. I have the same on one window, the mark doesn't change whatever the weather.

 

[securespark]

Can you get hold of a wet-o-meter? If the plaster is damp, it should squawk.
Plus, what does the area over the door look like?