31 Days in November?

[Volcano Man]

To suppliment Glenns' answer:

I am almost positive that the 31st November date in the weather file would be skipped, as the engine does match the date up with the date in the weather file to determine what the weather forcast is for that day. Since there is not 31 days in November, this line would be skipped. So it is not the other way around in that the engine does not get the day from the weather file.

There is usually a lot of copying and pasting involved with making weather.dat files. The designer usually creates one month, then copies and pastes it and then changes the month numbers and the weather values so that the entire thing does not have to be typed from scratch. No doubt that an oversight like this would occur from copying and pasting the month before but it shouldn't cause a problem.