Sip, older spelling Zip, is the red conjunction, the partner of Wo, the black conjunction, that precedes it. In colonial Yucatec sources the word Sip is also a name associated with the deer and with hunting, and hunters are described as observing the month, which is one of the places where a Haab month carries a recognisable occupational association rather than only a name.
That association should not be pressed into a season. Because the Haab has no leap-day correction its 365 days lose ground against the true solar year by about a quarter of a day annually, so the month drifted steadily through the real calendar over the centuries and cannot have marked a fixed hunting season for long. Whatever seasonal fit the name once had was true of a particular era and not of the calendar as such.
A Maya date does not name a month and a number in the way a European one does. It names a day in the 260-day Tzolk'in, by number and sign, and a position in the 365-day Haab, by day and month, and the two together form the Calendar Round, which repeats only after 18,980 days, a little under fifty-two years. Within the Haab the days of a month are numbered from zero to nineteen, and the zero day is not called first but seated, the seating of the month, a usage the Classic inscriptions write with its own glyph.