Car fan is really loud when stationary and just after the car is switched off?

I've got a 2010 Ford KA which I've had for 2 years in the last few days I noticed a fan comes on when I'm stationary and it's really loud for about a minute when I turn the engine off. Does anyone know what this could be?

Added (1). Themostat was broken - phew! Not a hug expense to correct!

Right above the radiator in the engine bay, you'll probably notice that there's a sticker warning you that the car's fan can turn on at any time. The sticker usually has a crude picture of fingers getting cut off by a fan blade along with the written warning for the exact reason you're seeing - a car's radiator fan(s) can turn on even if the engine isn't running. As long as the fan(s) aren't running for more than a couple of minutes and killing the battery, I wouldn't worry about it.

Its probably normal, when you are statioary your engine gets hotter because there's no air running through the radiator to cool it down so the fan kicks on to either push or pull air through the radiator when the car is at standstill (basically simulating the air that would be pushed through naturally when on the road) my cars fan stays on for a few seconds after its turned off, not a full minute though, thats strange. However you probably have a straight blade fan (louder type) and it probably running at its highest speed. Either way i wouldnt worry.

Probably normal. Fans normally come on when stationary and often when engine turned off. Tell us what unusual behavior you are noticing? Is it louder than normal? Is it staying on too long? Has anything changed? It may be a 2 speed fan and the high speed coming on when it should not?

Well that is because it is a fan. And it comes on to help cool the engine down espically when you are in stop and go traffic or the car is stationary. Also on some car, the fan kicks on for a bit to help cool the car down more when it is turned off.

Change fan clutch

Flip the hood open and see if the radiator cooling fans are needlessly running. Fans do not circulate coolant. That's the job of the water-pump.