Don't worry - normal thing, we all have the same, foggy autumn - foggy brain and thoughts ;)... but really - autumn time is in one way - very creative time of the year, all the colours and changing nature makes me feel really full of insprations, but in other way - I would just sit down with a bottle of wine, somewhere with a nice view outdoor, and just do nothing - writing clear thoughts is a problem when Your thoughts are flying high above Your head...
But I do love the foggy weather, and I find it very inspiring! ;) I don't know what it is, but usually it's not about the weather even when it comes to writing, it effects a lot more on the photographic inspiration, obviously.