Blue Hill Observatory
The Blue Hill Observatory and Science Center sits on the summit of Great Blue Hill in Milton and has recorded the weather every day since February 1, 1885. It says that's the oldest continuous weather record in North America. It's a National Historic Landmark run by a nonprofit. Visitors can tour it for a fee from February to December, but there's no car access: you hike or walk the summit road up.
Before you plan a visit around it, check the observatory's website. It reported vandalism to its historic building on June 29, 2026, and has posted a temporary closure notice on its home page.
Blue Hill Observatory at a Glance
Why the Blue Hill Observatory Matters
Since 1885, someone has climbed Great Blue Hill and recorded the weather every single day. The observatory says that unbroken run, now more than 140 years, is North America's oldest continuous weather record, and it quotes the World Meteorological Organization calling it the most homogeneous climate record in North America. The observatory says NOAA, NASA and universities rely on the data.
DCR's Blue Hills page calls the observatory a crowning feature of the reservation, and DCR's map lists it as a National Historic Landmark. The building is over 130 years old and was built in stages on the granite summit.
Tours and Prices
The observatory lists three public tour options on its visit page:
- Discovery Tour (self-guided): $10, free for members. The 360-degree view from the top of the observatory, the Mish Michaels Exhibit Hall and the History Room.
- Observatory Insider (guided, about an hour): $15, or $5 for members. The whole building, including the Weather Observation Data Center, with a visit to the top of the tower. A $5 add-on visits the instrument enclosure.
- Sunset Summit Tour: $125, by reservation only, with a look at the historic instruments as it gets dark.
Children under 5 get in free, and the gift shop is free to enter. DCR's map notes the shop sells drinks and trail snacks, which is welcome at the top of the climb. Tickets can be bought online.
Hours
The observatory is closed every Monday and for the whole month of January, plus Thanksgiving, Christmas Eve and Christmas Day. Its posted public tour hours are:
- Tuesday to Friday, February to December: 10 a.m. to 2 p.m.
- Weekends and holidays, February to May 24: 10 a.m. to 4 p.m.
- Weekends and holidays, May 25 to October 12: 10 a.m. to 5 p.m.
- Weekends and holidays, October 13 to December 31: 10 a.m. to 4 p.m.
Guided tours by appointment are available any day of the year, according to the observatory. Given the 2026 vandalism notice, confirm before you go.
How to Get to the Observatory
There's no public parking at the top. The usual approach is from the Trailside Museum lots on Route 138: take the Route 138 exit from I-93 or I-95 in Canton, drive north about a mile through one traffic light, and park in the Blue Hills Ski Area and Trailside Museum area on the right.
From there, either hike the red dot trail, about 1 mile and 1 to 1.5 hours by DCR's estimate, or walk the paved summit road (details on our Great Blue Hill page). DCR lists the road at 0.9 mile one way, with an average slope of 9 percent and a maximum of 20 percent. The road is closed to public vehicles, though the observatory says special arrangements can be made for specific vehicles if you contact it ahead.
The observatory's mailing address is 1 Observatory Service Road, Milton, MA 02186, but don't put it in your GPS expecting to drive there.
Accessibility
Many public rooms are accessible to visitors with limited mobility, the observatory says, but the observation room and upper tower can only be reached by stairs. The hilltop around the building is rocky and uneven. Exhibits can be moved to accessible rooms, and the observatory asks visitors who need accommodations to call 617-696-0562 or email info@bluehill.org.
Combine It With Eliot Tower
The observatory shares the summit with Eliot Tower, the stone lookout DCR maintains on Great Blue Hill. DCR's hiking directions invite you to climb it for a panoramic view of Boston. A visit to both makes a good half-day with the hike.
Blue Hill Observatory FAQ
Is the Blue Hill Observatory open to the public?
Yes, for paid tours from February to December, closed Mondays and all of January. In 2026 the observatory reported vandalism and posted a temporary closure notice, so check bluehill.org before you go.
How much does it cost to visit the Blue Hill Observatory?
The self-guided Discovery Tour is $10 and the guided Observatory Insider tour is $15. Members pay less, children under 5 are free, and the gift shop is free to enter.
Can you drive to the Blue Hill Observatory?
No. The summit road is closed to public vehicles. Park at the Trailside Museum lots on Route 138 and hike the red dot trail or walk the 0.9-mile paved summit road.
How old is the Blue Hill Observatory weather record?
It goes back to February 1, 1885, with a reading every day since. The observatory says it's the oldest continuous weather record in North America.
Facts from the DCR page for Blue Hills Reservation.