Complete school year calendar for Mount Sinai School District, Suffolk County. Includes all holidays, breaks, half days, and important dates from September 2025 through June 2026.
| Event | Date(s) | Status |
|---|---|---|
| First Day of School | September 2, 2025 (Tue) | School Opens |
| Rosh Hashanah | Sep 23–24, 2025 (Tue–Wed) | No School |
| Yom Kippur | Oct 2, 2025 (Thu) | No School |
| Columbus Day | Oct 13, 2025 (Mon) | No School |
| Veterans Day | Nov 11, 2025 (Tue) | No School |
| Thanksgiving Recess | Nov 26–28, 2025 (Wed–Fri) | No School |
| Winter Recess | Dec 24, 2025 – Jan 2, 2026 | No School |
| MLK Day | Jan 19, 2026 (Mon) | No School |
| Mid-Winter Recess | Feb 16–20, 2026 (Mon–Fri) | No School |
| Eid al-Fitr (Supt. Conf. Day) | Mar 20, 2026 (Fri) | No School |
| Spring Recess | Apr 1–10, 2026 (Wed–Fri) | No School |
| Memorial Day | May 25, 2026 (Mon) | No School |
| Juneteenth | Jun 19, 2026 (Fri) | No School |
| Last Day of School | June 26, 2026 (Fri) | School Closes |
Complete month-by-month calendar from September 2025 to June 2026. Every day is color-coded so you can see school days, holidays, and breaks at a glance.
The Mount Sinai School District is a compact, high-performing K-12 district serving approximately 2,800 students in the hamlet of Mount Sinai, Suffolk County, on Long Island's North Shore.
Adjacent to Stony Brook University and Brookhaven National Laboratory, Mount Sinai attracts families who value academic excellence in a small-community setting. The district operates three schools — Mount Sinai Elementary, Mount Sinai Middle School, and Mount Sinai High School — and is known for strong AP pass rates and competitive Science Olympiad programs. Compare with Commack and Smithtown.
The first day of school is Tuesday, September 2, 2025.
Winter Recess runs from December 24, 2025, through January 2, 2026.
Spring Recess is April 1–10, 2026 (10 days including weekends).
Yes. Mount Sinai observes two days of Rosh Hashanah (Sep 23–24, 2025) as well as Yom Kippur (Oct 2).
The last day is Friday, June 26, 2026.
Mount Sinai is located adjacent to Stony Brook University (less than 5 miles), giving students access to university-sponsored STEM enrichment programs.
The district builds emergency closure days into the calendar. If unused, some may be returned as "give-back" days near Memorial Day.
Yes — Eid al-Fitr (March 20, 2026) is a Superintendent's Conference Day with no school for students.
Data Source: This calendar is based on projected dates derived from historical Mount Sinai School District scheduling patterns.
Disclaimer: This website is not affiliated with, endorsed by, or connected to Mount Sinai School District or the New York State Education Department (NYSED). For the most current and official calendar, please visit www.mtsinai.k12.ny.us.
Dates are subject to change. Religious holiday dates are approximate and based on projected lunar calendar calculations.
Last updated: March 12, 2026