Mushy front end

[ffron69]

Sorry if this has been covered I am not so good with the search function here...

Went for a good ride today, got home & notice the front end is "diving" a lot when I apply the front brakes. Pushing down on the handelbars easily I can bottom out the front forks, backing up down hill & applying the front brake I can fully extend the forks very easy. I don't think it was near like this before I left this morning but I guess I could be wrong. Bike has 10,350 miles on it...Ideas? Could the fact it is fairly cold (low 50s) have anything to do with it?

Thanks