The simple answer is that the traditional Hebrew calendar of today (which is the modern adaptation of the calendar established by Hillel II), rigidly incorporates the 19-year "Metonic Cycle" into the determination of which calendar years must include a "leap month" - and in 2016, the "leap month" we see in February is simply not needed. If "calendar stuff" is not your bag and you don't want to continue reading to find out why the traditional calendar is wrong in 2016, suffice it good enough to know that the current Hebrew year, 2015-2016, is not the correct year for the intercalated month. Passover falls in the proper time without the added month. If you'd like to know more, please read on…
The problem, graphically
Today's traditional Hebrew calendar is often referred to as the "Hillel Calendar", but that is not quite fair to Hillel II for his recommendation in the 4th Century CE to adopt the Metonic Cycle is only part of the many problems with today's traditional Hebrew calendar which came to be over many centuries following Hillel II. So, let's begin understanding the problem. We must begin with how the "1st month" is determined, then address the need for the "leap year" and finally discuss the impact of the added month to the Feast dates for 2016.
How the "1st Month" is determined
The Hebrew calendar is a "lunar-solar" calendar which basically means the moon determines the months while the sun determines the year. In Genesis, we are told that the sun, moon, and stars are for "signs, seasons, days and years" (Genesis 1:14). Beyond that one verse there are no instructions in scripture for keeping the calendar. We are only told later (Exodus 12) that the month of spring, Abib (today called Nisan), the month of the Exodus, would be the "first month of the year" and that Passover and the Feast of Unleavened Bread are to be "at the time appointed in the month Abib [Nisan]" (Exodus 23:15). So the month of Abib sets the calendar for the whole year. How is it determined?
There are 12 lunar months in 1 solar year. But the year (not the calendar month) is determined by the sun and stars. (If there were no moon at all, we would still know the "year"). And it is the sun which causes and determines the "seasons" (winter, summer, planting and harvest) not the "moedim"). It is the moon which determines the "month" and the "season" (i.e., the "appointed times", the moedim) of that month. (Since the agricultural seasons are absolutely tied to the sun, and the "moedim" are tied to both the month, and the season of the year, the word "moed" has become largely confused and sometimes people think the "month" is tied to the agricultural "signs", i.e., the barley crop. But go back and look at Genesis 1:11-18 and see that even though YHWH made the grasses and seed bearing plants first, before the sun, moon, and stars were "placed" (verse 17), it's only when the sun, moon, and stars were "placed" that "day and night" and the agricultural seasons began. Had YHWH not placed the sun, moon, and stars as He did, the plants he created would have required some other annual schedule mechanism to grow and seed, for without the seasons created by the sun, plants would not have the life-cycles we have always known. And note that verse 14 does not say: "Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days and the ripening of the crops for the years". Ripening crops is an earth sign, and no verse says any earth sign trumps a heaven sign.
Man has known for thousands of years the "signs" in the sun and stars that identify one complete year. There are four very clear "divisions" of the year, roughly 90 days or 3 months apart. These divisions are the northernmost point of the sun which marks summer, the southernmost point of the sun which marks winter, the point when the sun is exactly due east as it is moving from south to north which marks spring, and the point when the sun is exactly due east as it is moving from north to south which marks the fall or autumn. We know from Exodus that "Abib" was the "month of newly-ripened grain", (or the "month of spring") and that crops begin to ripen in the season of spring, and we know that the exodus began in spring, and that the night of the exodus (14-15 Abib), it was already spring. That is, the sun had been at the point when "spring" begins when the exodus began. (It's very important to understand that the crops ripen because of the month it is, not that crops determine what month it is.) So the commandment to keep the feast "at the time appointed in the month Abib [Nisan]" (Exodus 23:15), means that the calendar must keep Abib as close as possible to spring (today we call it the "Vernal Equinox"), and then the moed of Passover can happen. Thus, the month of Abib is the month when Passover falls on or after the Vernal Equinox. (This is why the inserted month is not needed in 2016. Without adding the leap month, Passover falls after the Vernal Equinox in March, 2016. Therefore the "real" moon in early 2016 indicates no leap month is required.)
Many will argue that there is nothing in scripture requiring Passover to fall on or after the Vernal Equinox. While that is a true statement, there are also no scriptures requiring waiting for the barely crop to ripen to identify the month of Abib, nor are there any scriptures calling for the month to begin with the sighting of the crescent moon. But the sages do interpret Deuteronomy 16:1 "Observe the month of Abib and offer a passover sacrifice to the LORD your God, for it was in the month of Abib, at night, that the LORD your God freed you from Egypt." (JPS) to mean spring must come first, then Passover. That means that the "month of spring" is the month in which Passover falls after spring has begun. Again, the start of spring is determined by the sun, so the "month of spring" must be the new moon that places Passover in the month of spring which keeps the calendar in compliance with Exodus 12 and 23:15.
The need for the "leap year"
A calendar year of 12 lunar months will often keep Passover after the Vernal Equinox without doing anything, but at the end of the 2nd or 3rd year, due to the fact that the lunar year (12 lunar months) is actually short of the solar year by about 11 days, sometimes Passover would fall before the Vernal Equinox. In that case, since the new moon of Abib would happen too early, and Passover would fall before the Vernal Equinox, and not be "in" spring, an additional lunar month must be added. Therefore in any year, if the new moon of Abib [Nisan] would cause Passover to fall before the Vernal Equinox, an extra month is added to the year coming to an end, therefore the year which is ending will have 13 months and is a "leap year" - the rabbis call it the "embolismic year". The added month "moves" the month of Abib forward by one month, which then establishes Passover again at the right time, after the Vernal Equinox, and the calendar is "good" for two or three years until an embolismic year is needed again.
Astronomers of ancient Babylon discovered that in the span of 19 solar years, there were exactly 235 complete lunar months. ("Exact" here means to within about 2 hours - pretty remarkable.) If one counted 19 solar years and the "lunar years" of 12 months by counting new moons, they'd see that in "lunar years" 19 solar years is the same as 19 years (of 12 lunar months) plus 7 months by the moon. The astronomer Meton, about 432 BCE wrote that if an intercalary month were added to the lunar calendar 7 times in 19 years, then at the end of the 19 solar years, the number of lunar years would exactly match - i.e., 19 solar years = 19 lunar years. Meton laid out a "schedule" of when the additional month might be added. He said the leap years would be years 3, 6, 8, 11, 14, 17, and 19. (You can see the sequence of years the extra month is added: 3, 3, 2, 2, 3, 3, 2.)
This is all well and good - mathematically. But in reality, if you actually used the moon to indicate which year should be the leap year, the "schedule" of intercalary months may instead need to be (for example) years 3, 5, 7, 10, 13, 16, 19. The real moon simply does not follow a repeating 3, 3, 2, 2, 3, 3, 2 cycle. And this is the problem with 2016. According to the real moon, 2015-2016 (the current year) does not need to be a leap year, while the next Hebrew year (2016-2017) does need to be a leap year. But the traditional Hebrew calendar, with its rigid, preplanned schedule of leap years, ignores the real moon and inserts the leap month of Adar I, by schedule, into the 2015-2016 calendar year when it is not needed.
Impact to the 2016 calendar
Since the traditional Hebrew calendar inserts a month in early 2016, the whole calendar year from February 9, 2016 to February 27, 2017 makes every holiday observance a month late. As a result, the traditional Hebrew calendar will not match the calendar of The Refiner's Fire the whole period. So here are the dates of the Feasts in both calendars:
The rigid application of the Metonic cycle without regard to the "real" moon is the major problem with the 2016 traditional Hebrew calendar which applies an unnecessary leap month manifested in February, 2016. That unnecessary month causes all the Holy Days for 2016 in the traditional calendar to be one month late. The many other problems with the modern traditional calendar include the use of the "molad" of the moon, which is an "average" lunar month which sometimes causes the 1st of the month to be a day early or a day late, and the rules for "postponement" where the 1st of Tishri is held 1, 2, or 3 days so Yom Kippur will not fall on a Friday or a Sunday. We believe the use of the "average moon" to calculate the 1st day of the month is wrong. We also believe the "postponement" rules are wrong, as they are simply not scriptural.
We realize this issue will cause no end of concern, confusion, and argument and some will simply say "follow the accepted calendar for the sake of commonality". We can't do that. In the end though, we don't argue "which calendar" is better or "which calendar" should be used. We believe it is far better to observe the Holy Days rather than not observe them, so we at The Refiner's Fire recommend you learn the meaning of the Holy Days, and observe them by whichever calendar you chose. If you have a congregation celebrating by the traditional calculated calendar, then by all means, celebrate with them. That beats the "rest of the world" which does not observe any of the commanded Holy Days in favor of "man-made" holidays which masquerade to be about God.