What are the earliest and latest possible dates, on the common Roman calendar, for the Hebrew Festival of Shabuot, the Feast of Weeks, or Pentecost?

It always falls 49 days from the second day of Passover. (7 weeks ). Those 49 days are known as the Counting of the Omer. (The 33rd day – Lag B’omer) is considered a holiday to spend outdoors.

So Shavuot (we Jews don’t say Shabuot) is dependent on the date of Passover (Pesach) – Shavuot doesn’t stand on its own.

Pesach is always the 15th day of Nissan. Depending on whether the Jewish year is a 12-month or a 13-month year (with Adar 2) – Pesach can be anywhere between mid-March and late April.

Quick answer: consult a Jewish calendar. The date is variable.

Yeah, I figured I’d have to do that.

But thanks for all the concise information. It was very helpful.
Even the information that its best to consult a calendar was helpful,

Some answers really do have too many variables.

Although the first Christian Pentecost was on Shavuot, on the Christian calendar it is the seventh Sunday after Easter.

The earliest Easter can be is March 22 and it can be as late as April 25. So Pentecost can be anywhere from May 10 to June 13.