A weekly feature of Torah Tidbits to help clarify practical and conceptual aspects of the Jewish Calendar, thereby better fulfilling the mitzva of HaChodesh HaZeh Lachem...

Rosh Chodesh Sh'vat is always one day, because Tevet always has only 29 days. (In our fixed calendar, that is.) Sh'vat itself always has 30 days.

Rosh Chodesh Shvat (and all the other days of the month) can fall on any of 5 days of the week; there are only 2 days of the week that it cannot be. (This is different from the majority of calendar dates, which have 4 possible and 3 impossible days of the week.)

The stats for Rosh Chodesh Sh'vat (and TU b'Shvat, as well - and the 8th, 22nd, and 29th, for that matter) are 29.9% of the time it is on Shabbat, 27.9% on Monday, 20.1% on Thursday, 18.1% on Wednesday, and only 3.9% on Tuesday. Never on Sunday or Friday.

The MOLAD of Sh'vat is THU (Jan.6) 18h 40m 13p (which is 6:20pm Israel Time). Actual Molad - 8:13pm