It's possible I'm misunderstanding something, but the following is a historical METAR report from January 31st, 2000:

'KUAO 310053Z AUTO 31009KT 10SM -RA FEW046 BKN055 OVC070 05/00 A2980 RMK AO2 RAB52 SLP094 P0000 T00500000 TSNO $'

When using this library I get the following exception:

>>> Metar.Metar("KUAO 310053Z AUTO 31009KT 10SM -RA FEW046 BKN055 OVC070 05/00 A2980 RMK AO2 RAB52 SLP094 P0000 T00500000 TSNO $")
[... stack trace elided ...]
ParserError: _handleTime failed while processing '310053Z AUTO 31009KT 10SM -RA FEW046 BKN055 OVC070 05/00 A2980 RMK AO2 RAB52 SLP094 P0000 T00500000 TSNO $ '
	day is out of range for month

I'm happy to hear that I've misunderstood something or I'm using it wrong. I'm also happy to patch the bug myself if it is indeed a bug.

Thanks for the library!