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Arnold Arboretum
Hobo weather station

Weather Data at the Arnold Arboretum

Collection of detailed weather data has been an ongoing interest at the Arnold Arboretum for nearly a century. Over the years, various departments and members of staff have observed and documented weather on the grounds, particularly in terms of plant hardiness, microclimates, seasonal plant phenology, and extreme weather events. Collection procedures have ranged from daily handwritten observations to today’s highly automated systems that broadcast live weather data online.

The study of weather at the Arboretum developed through an interest in how meteorological conditions (particularly temperature) can affect the flora inhabiting our landscape. In Alfred Rehder’s original publication of the Manual of Cultivated Trees and Shrubs (1927), the first Arnold Arboretum Hardiness Zone Map for the US was created to help inform the public about the limitations of plants in surviving minimum cold temperatures. Donald Wyman and other Arboretum staff periodically updated these maps, which were featured in various publications.  In 1960, the USDA published their first standardized national Plant Hardiness Zone map; most recently updated in 2012, it is still considered to be the most reliable source of plant hardiness information. A review [pdf] of the Arboretum and USDA Hardiness Zone Maps was published in Arnoldia.

Hardiness Zone Map 1927

Image courtesy of Arnold Arboretum Archives. First published in 1927 in the Manual of Cultivated Trees and Shrubs by Alfred Rehder.

Staff began recording weather data in 1965 from a weather station installed at the Dana Greenhouses, a practice which continues today. In early winter 2011, a new weather station was added at the Arboretum at the Weld Hill Research Building. With the ability to report and share information online, precise weather data can now be obtained by anyone with access to a computer or mobile device. This diagnostic tool is a useful resource for staff and the visiting public, providing a highly localized and robust picture of our weather.

The application of these data can inform horticultural management strategies, enhance record keeping, and facilitate comparisons with field observations. The station utilized by the Arboretum features a highly modular design allowing for seamless integration of a wide variety of climatic sensors. Currently these sensors monitor temperature, relative humidity, barometric pressure, rain, leaf wetness, solar radiation, soil temperature, and wind speed and direction.

In addition to our central weather station, the Arnold Arboretum gathers data from 18 micro-stations dispersed throughout the landscape. These micro-stations were installed in 2008 to help identify microclimates on the grounds. This information is highly valuable for both mapping climate patterns over time and for locating areas of the landscape where plants of marginal hardiness may be sited to improve their chances of survival.

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Hardiness Zone Map 1967

Hardiness Zone Map 1967. Image courtesy of Arnold Arboretum Archives.

Hardiness Zone Map 1948

Hardiness Zone Map 1948. Image courtesy of Arnold Arboretum Archives.

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