| 1776 | An act of the Massachusetts legislature declared that the
summit be named Great Blue Hill. Beacons were established and the summit was used
as a vantage point during the Revolutionary War. |
| 1778 | May 30 Construction began on a forty-foot stone and wood observing
platform. It was blown down four years later, rebuilt, and remained for many years. |
| 1830 | A state trigonometric survey precisely established the position of Great Blue Hill and the height above mean sea level as 193.69 m (635.05 feet). |
| 1845 | July U.S. Coast Survey Corps of Engineers opened a new road to the summit near the site of the current road. |
| 1861 | Founder of the Blue Hill Observatory, Abbott Lawrence Rotch,
was born in Boston. |
| 1884 | May Rotch graduated from the Massachusetts Institute of Technology with a degree in engineering. |
| 1884 | Aug 5 Rotch first documented the idea of building a weather observatory on Great Blue Hill. |
| 1884 | Sep 1 Construction began on the original observatory, which consisted of a two-story tower and living quarters. |
| 1885 | Feb 1 The Observatory was occupied and official daily observations began on the summit. |
| 1886 | Jan A Campbell-Stokes sunshine recorder, the first of its kind in the United States was first used. It remained in service until it was stolen in June, 1995? and replaced with a modern reproduction. The original was recovered and is stored in the Observatory museum.
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| 1887 | Dec The oldest mercury barometer still in daily use at the Observatory was put into service. |
| 1889 | A new east wing library was opened. |
| 1893 | The Metropolitan District Commission acquired land around Blue Hill for parkland that would become the Blue Hill Reservation. |
| 1894 | Aug 4 The first atmospheric sounding in the world was accomplished at Blue Hill with a kite carrying a thermograph to a height of 2030 feet above mean sea
level. |
| 1900 | Jul 19 The highest kite sounding was made from Blue Hill to a height of 4,815 m (15,790 feet). |
| 1902 | A west wing was added to the living quarters that became the Observatory library. |
| 1905 | A concrete wall and iron fence were erected around the Observatory. |
| 1906 | Sep 1 Rotch was appointed Professor of Meteorology at Harvard.
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| 1908 | Jun 4 A new three-story concrete tower, replacing the original tower, was completed. |
| 1912 | Apr 7 Abbott Lawrence Rotch died. The Observatory program was taken over by Harvard University. |
| 1913 | Oct 1 Alexander George McAdie was appointed as the new director of the Observatory. |
| 1914 | Jan 16 Electric lights were first put into use at the Observatory. |
| 1931 | Charles Franklin Brooks, founder of the American Meteorological Society in 1919, became the third director of the Observatory. |
| 1932 | Oct Mount Washington Observatory was reopened. |
| 1933 | Nov 7 Daily radio communications were established between Blue Hill and Mount Washington. |
| 1934 | Feb 9 Coldest temperature ever recorded at Blue Hill, -21 degrees F. |
| 1935 | Apr 17 The first radio-meteorograph transmission of temperature data from an airplane was received at Blue Hill from a height of 17,000 feet. |
| 1935 | Dec 23 The first radio-meteorograph transmission of pressure and temperature data from a balloon was received at Blue Hill from a height of 52,500
feet. |
| 1938 | Sep 21 Greatest wind gust recorded at Blue Hill of 186 mph occured from the south during the Great New England Hurricane of 1938. The highest five-minute average wind speed was 121 mph from the south. |
| 1941 | Dec 14 The Observatory was occupied by the U.S. Army for several weeks to spot and report airplanes. |
| 1949 | Aug 10 Hottest temperature ever recorded at Blue Hill, 101 degrees F. It occured once more in 1975. |
| 1953 | Jun 9 Debris from the Worcester tornado was recovered on Blue Hill. |
| 1954 | Nov 16 U.S. Air Force Geophysical Research Directorate established a weather radar laboratory on the summit that remained until November, 1961. |
| 1955 | Aug 19 The Observatory record for the greatest 24 hour rainfall of 9.93 inches was recorded during Hurricane Diane. The event also established the single storm rainfall record of 12.77 inches. |
| 1957 | Sep 1 John H. Conover became acting director of the Observatory and continued until June, 1958. |
| 1958 | Jul 1 Richard M. Goody became Blue Hill director. |
| 1958 | Oct The Blue Hill Observatory library was transferred from the station to the Gordon McKay Library in Pierce Hall, Harvard University. |
| 1959 | Jul 1 The observation program at Blue Hill was taken over by the National Weather Service. |
| 1960 | Sep 12 Second highest Blue Hill wind gust of 140 mph was recorded during Hurricane Donna. |
| 1962 | The first measurements of airglow, the emission from atomic oxygen during the day, were made at Blue Hill by Goody and John Noxon. |
| 1971 | Oct 1 Ownership of the Observatory was passed from Harvard University to the Metropolitan District Commission. Goody retired as director. |
| 1975 | Aug 2 Hottest temperature ever recorded at Blue Hill, 101 degrees F. |
| 1976 | Jan 1 Blue Hill Observatory was officially listed as a Reference Climatological Station by the World Meteorological Organization due to the length and homogeneity of its climate record. |
| 1980 | Sep 27 The Observatory is placed on the National Register of Historic Places' |
| 1981 | Jun The Blue Hill Weather Club and Museum was established by Dr. William Minsinger. |
| 1985 | Feb 1 Centennial observation day was marked with the rededication of
a monument to the Observatory's founder, Abbott L. Rotch. The stone monument was inscribed with a summary of the Blue Hill weather record for the past century. |
| 1989 | Dec The Blue Hill Meteorological Observatory was listed as a National Historic Landmark by the U.S. Park Service. |
| 1996 | Apr 10 Largest Blue Hill seasonal snowfall of 144.4 inches was set in the last storm of the 1995-96 season. |
| 1997 | Sep Extensive renovations of the Observatory began. |
