Let's take a look back at how well the forecast for the Rolex 24 verified.
The low temperature forecast didn't work out as well on Thursday night and Friday night, but I don't think anyone will be too critical for missing the overnight temperatures that were warmer than forecast. I suspect the reason that temperatures stayed so mild overnight was that the wind each night stayed up, between 8 and 14 mph. Calm winds allow for the temperatures to drop lower than when winds stay up. The low temperature forecast Saturday night during the race was good, which was probably the most important night to get right.
There was more sunshine on Sunday than I expected, which allowed temperatures to rise to 77 degrees that afternoon, about 4 to 5 degrees higher than forecast.