I have a Planet Bike Protege 9.0 bike computer. It has a thermometer on it but I'm doubtful to its accuracy. I say that because it never matches the the thermometer on the bank sign. But who's to say how accurate that one is. But it does give mis-readings in direct sunlight.
But let me add. On cloudy days, and when I ride in the dark. It gives close readings that are pretty accurate or close to it.