'06 Altima reading wrong outside temp?

[FAUguy]

I have an '06 Altima 2.5S Special Edition. It reads the outside temp and displays it under the mileage.
I have noticed that it shows 5-7 degrees more (warmer) than it is.
I have a 98 LeSabre and it always matched up the temp (within 1-2 degrees) with the temp on the Weather Channel.
If I put both cars together, there is a 5-7 degree temp difference between them.
It's not a MAJOR problem, but I'm curious to know why the Altima is reading more.
Could it need to be calibrated, or is it normal?

[FAUguy]

On my way home today it showed 79 and then went down to 78. The temp on the weather channel was 68.