The Blue Hill Meteorological Observatory in
Milton, Massachusetts
Milton is a town in Norfolk County, Massachusetts, United States. Milton is an immediate southern suburb of Boston, Massachusetts. The population was 28,630 at the 2020 United States census, 2020 census.
Milton is located in the relatively hilly ...
is the foremost structure associated with the history of weather observations in the United States. Located atop
Great Blue Hill about 10 miles south of
Boston
Boston is the capital and most populous city in the Commonwealth (U.S. state), Commonwealth of Massachusetts in the United States. The city serves as the cultural and Financial centre, financial center of New England, a region of the Northeas ...
,
Massachusetts
Massachusetts ( ; ), officially the Commonwealth of Massachusetts, is a U.S. state, state in the New England region of the Northeastern United States. It borders the Atlantic Ocean and the Gulf of Maine to its east, Connecticut and Rhode ...
, it is home to the oldest continuous weather record in
North America
North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
, and was the location of the earliest kite soundings of the atmosphere in North America in the 1890s, as well as the development of the
radiosonde
A radiosonde is a battery-powered telemetry instrument carried into the atmosphere usually by a weather balloon that measures various atmospheric parameters and transmits them by radio to a ground receiver. Modern radiosondes measure or calculat ...
in the 1930s.
Founded by
Abbott Lawrence Rotch in 1884, the observatory took a leading role in the newly emerging science of meteorology and was the scene of many of the first scientific measurements of upper atmosphere weather conditions, using kites to carry weather instruments aloft. Knowledge of wind velocities, air temperature and relative humidity at various levels came into use as vital elements in weather prediction due to techniques developed at this site. By 1895 the observatory was the source of weather forecasts of remarkable accuracy. On August 4, 1894 the first atmospheric sounding in the world was accomplished at the observatory, with a weather kite carrying a thermograph 2,030 feet above sea level. On October 8, 1896, a record of 8740 feet (2,665 m) was achieved for a weather kite. During the
Great New England Hurricane of 1938, the observatory measured the strongest wind gust ever directly measured and recorded in a hurricane at 186 mph (299 km/h).
The observatory remains active to this day, continuing to add to its database of weather observations now more than one hundred years old, and stands as a monument to the science of meteorology in the United States.
History
Site
The Blue Hill Meteorological Observatory was founded by American
meteorologist
A meteorologist is a scientist who studies and works in the field of meteorology aiming to understand or predict Earth's atmosphere of Earth, atmospheric phenomena including the weather. Those who study meteorological phenomena are meteorologists ...
Abbott Lawrence Rotch in 1885. By the time he graduated from the
Massachusetts Institute of Technology
The Massachusetts Institute of Technology (MIT) is a Private university, private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of moder ...
in 1884, Rotch had conceived and carried into execution his plans for the erection of a meteorological observatory on the summit of Great Blue Hill, ten miles south of
Boston, Massachusetts
Boston is the capital and most populous city in the Commonwealth (U.S. state), Commonwealth of Massachusetts in the United States. The city serves as the cultural and Financial centre, financial center of New England, a region of the Northeas ...
in the
Blue Hills Reservation, a 6,000-acre (24 km²) public park managed by the
Massachusetts Department of Conservation and Recreation. Rotch chose the site because the elevation of 635 feet was the highest point within ten miles of the Atlantic Ocean, on the East Coast south of central Maine. The Observatory was founded as a weather station and research facility. This location afforded early weather scientists a unique opportunity for recording extremes of weather and experimenting with weather-recording instruments.
The observatory building was completed by the end of 1884 and the first regular observations were begun on February 1, 1885. Rotch became the first director of the observatory and maintained it at his own expense until his death in 1912 when he bequeathed it to
Harvard University
Harvard University is a Private university, private Ivy League research university in Cambridge, Massachusetts, United States. Founded in 1636 and named for its first benefactor, the History of the Puritans in North America, Puritan clergyma ...
with an endowment of $50,000, which grew to $111,000 in the twelve years after his death.
The building

Construction of the observatory was started by Rotch in 1884 using his own private funds, and designed by architects
Rotch & Tilden. The original structure consisted of a two-story circular tower and an adjoining housing unit which contained two bedrooms, a dining room and a kitchen. In 1889, a two-story east wing was added to provide additional working space for research, domestic chores, and the library.
In 1902, a two-story west wing containing a new library was added to provide additional work space. A steel fire door and brick wall connect the library to the earlier masonry structure. A timbrel vault (18 by 35 ft) of cohesive tiles spans the library. The timbrel vault tile roof is believed to have been installed by the Guastavino Company using an extremely tenacious mortar developed by
Rafael Guastavino, the founder of the firm.
Native stone, gathered from the summit of the Great Blue Hill, was used for the two-story tower, adjoining housing unit, and the east and west wings.
Copper sheathing was used for roofing. A stone wall and iron fence were erected in 1905 to provide security for the building and instruments and privacy for the staff. The original stone tower eventually proved to be unsuitable. Wind-driven rain penetrated its walls, damaging the instruments and records. Vibration from the instruments on masts atop the tower contributed to the structural problems.
In 1908, the original tower was demolished and a new reinforced three-story late
Gothic Revival
Gothic Revival (also referred to as Victorian Gothic or neo-Gothic) is an Architectural style, architectural movement that after a gradual build-up beginning in the second half of the 17th century became a widespread movement in the first half ...
concrete tower, 20 feet 6 inches wide and 32 feet 8 inches high was constructed in its place. The concrete construction of the tower was chosen specifically to provide the maximum amount of stability and durability in the event of high winds. The tower has a crenelated top and a cornice containing
dentils. The windows are double-hung sash with a shallow recessed arch over the windows on the first and second floors.

The new tower provided the durable weather-resistant, vibration-free environment necessary for accurate instrument readings. The first floor of the tower contains the director's office. The weather bureau is on the second floor and a laboratory and access to the roof are found on the third floor. Various wind gauges and other meteorological recording instruments are attached to the roof of the tower. The observatory still retains barometers and other instrumentation dating from the late 19th century. These instruments are used to calibrate the modern instrumentation to preserve the accuracy and integrity of the data base dating back to 1885.
In 1962, a metal tower containing a
siderostat for collecting the sun's rays and directing them by mirrors to an optical bench inside the observatory, was erected adjacent to the west wing for studies related to the upper atmosphere. This project was abandoned after a few years. This tower, with its mirrors still present, is no longer in use.
In 1980, the building was listed in the
National Register of Historic Places
The National Register of Historic Places (NRHP) is the Federal government of the United States, United States federal government's official United States National Register of Historic Places listings, list of sites, buildings, structures, Hist ...
as "Great Blue Hill Weather Observatory", as part of a multiple property nomination by the Commonwealth of Massachusetts entitled "Prehistoric and Historic Resources of the Blue Hills and Neponset River Reservations and Selected Adjacent Lands".
In 1981, the Metropolitan District Commission transferred responsibility for the observatory to the Blue Hill Weather Club, a local group of supporters, who plan to restore the observatory and establish a weather museum on the site. The observatory will be kept open to continue its record of continuous weather observations. The
National Weather Service
The National Weather Service (NWS) is an Government agency, agency of the Federal government of the United States, United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weathe ...
continues to operate an
Automated Surface Observing System at the site.
A white marble stone containing a summary record of climatological data from 1885 to 1984 and dedicated to the memory of Abbott Lawrence Rotch is located on the front yard of the building.
It was declared a
National Historic Landmark
A National Historic Landmark (NHL) is a National Register of Historic Places property types, building, district, object, site, or structure that is officially recognized by the Federal government of the United States, United States government f ...
in 1989 with name "Blue Hill Meteorological Observatory".
In 2021, a major $2 million renovation of the observatory began. The renovation is expected to be completed by April 2023. Many parts of the building are being upgraded, and the renovations include a new concrete wall, new ceilings, new windows, and increased weatherproofing.
During the renovation the observatory is closed to the public, however the gift shop is still functional as it has moved outdoors. The renovation has not interfered with daily weather observations taken at the observatory. When the renovation is complete, there will be new exhibits and programs.
History of its operations

Under Rotch's leadership, the Blue Hill Meteorological Observatory quickly became famous for its pioneering studies of the upper atmosphere. The study of cloud heights, directions and velocities that Rotch carried out at the Blue Hill Observatory made significant contributions to the knowledge of clouds in the early years of the 20th century.
Rotch continued to work at the Blue Hill Observatory until his death on April 7, 1912. Under the terms of his will, the observatory was given to Harvard University with an endowment of $50,000 for operating costs. Harvard operated the observatory until 1971 when it disassociated itself from the site. The Rotch endowment was kept by Harvard.
After 1912, the Blue Hill Meteorological Observatory continued to operate as an active meteorological observatory. Weather observations and recordings have continued to this day, providing modern meteorologists with a record of uninterrupted climatological observations that is unique in the world.
Since these recordings were obtained from the same site with virtually no environmental change, they provide an important index to
climate change
Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...
. This information is of special importance to students of climatic change, in an age where so many weather records are flawed by environmental and procedural changes, and by repeated moves of the observing site over a number of years. For this reason, the
National Oceanic and Atmospheric Administration
The National Oceanic and Atmospheric Administration (NOAA ) is an American scientific and regulatory agency charged with Weather forecasting, forecasting weather, monitoring oceanic and atmospheric conditions, Hydrography, charting the seas, ...
designated the Blue Hill Observatory one of 26 International Benchmark stations within the
United States
The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
.
During the 1950s, the site housed a research group that used
radar
Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track ...
to scan approaching thunder storms as far away as western New York State, as part of an inquiry into the causes of lightning. Findings by this group were instrumental in the development of the US
weather radar
A weather radar, also called weather surveillance radar (WSR) and Doppler weather radar, is a type of radar used to locate precipitation (meteorology), precipitation, calculate its motion, and estimate its type (rain, snow, hail etc.). Modern w ...
program. The installation consisted of a steel tower supporting a second-hand military radar set, several
Quonset hut
A Quonset hut is a lightweight prefabricated structure of corrugated galvanized steel with a semi-circular cross-section. The design was developed in the United States based on the Nissen hut introduced by the British during World War I. Hund ...
s and box trailers, surrounded by a chain-link fence. Group members were on call to monitor the radar whenever severe storms could be observed. Data were also collected from a network of amateur co-operative observers who corresponded by mail. This era coincided with the end of the long career of the famous Director of the Observatory, Dr. Charles Brooks, said to be one of the few who accurately forecast the path of the destructive
Hurricane of September, 1938.
Accomplishments
Since 1885, the staff of the observatory and others have documented the scientific work completed at the Blue Hill Observatory in almost 900 scientific publications. The Observatory's first century is a distinguished history of contribution to the development of meteorology. Measurements at the observatory have continued on a daily basis since the day it first opened in 1885, making the observatory one of the oldest continually active weather and climate monitoring stations in the United States.
[National Park Service]
Astronomy and Astrophysics: Blue Hill Meteorological Observatory.
Retrieved on 2006-12-03.
See also
*
List of astronomical observatories
This is a partial list of astronomical observatories ordered by name, along with initial dates of operation (where an accurate date is available) and location. The list also includes a final year of operation for many observatories that are no lon ...
*
List of National Historic Landmarks in Massachusetts
The Commonwealth of Massachusetts has a total of 192 National Historic Landmarks (NHLs) within its borders. This is the second highest statewide total in the United States after New York, which has more than 250. Of the Massachusetts NHLs, 5 ...
*
National Register of Historic Places listings in Milton, Massachusetts
References
External links
Blue Hill Observatory & Science Center- official site
{{Authority control
Meteorological observatories
Astronomical observatories in Massachusetts
National Historic Landmarks in Massachusetts
Milton, Massachusetts
Buildings and structures completed in 1885
Educational buildings on the National Register of Historic Places in Massachusetts
National Register of Historic Places in Milton, Massachusetts
Science museums in Massachusetts
Museums in Norfolk County, Massachusetts
Atmospheric sounding