Outside temperature wrong - faulty sensor or what?

Pakitt, I experience this behavior every day, from day 1. When I leave my company garage (inside garage about 16-17C, outside +33C) my car needs about an hour to get the valid temp.
Of cource A/C tries to heat up interior for the first 15 - 20 minutes so I'm turning it off (A/C off, lowering temp to keep air flow to face). As it gets warmer inside I'm increasing temp in 0.5C steps. When I reach 22C point turning A/C back on.

I've experienced this wierd behavior in other Toyotas after carwash but it never took so long. While dry Auris (in the same garage, same conditions) reached valid temps within 5 minutes.
I think there is something in reading firmware that implements too hard smoothing of the temperature readings.

Same applies in winter, when +16 is in the garage and -16C outside. It falls to about 0C within 3 minutes and next 16C after 30 - 45 minutes.

As others mentioned Toyota puts outside temperature sensor within front grill in their cars.

 

I am experiencing this problem too. I took my 2005 Prius through an automatic car wash today. An hour later, the Outside Temp was still reading 61 degrees, when in fact it was 75-80 degrees outside.

I'm assuming the sensor got wet, and/or blown by the strong air during the car wash. Should this problem resolve itself? The temperatures were always extremely accurate until today.

 

It should get back to normal after it dries out. Even manual mentions that after washing temperature reading may be wrong. All my cars had this problem. All get back to normal after 2 - 3 hours.

 

My temp gauge has indeed returned to normal. Thanks everyone.