Isle of Man Ronaldsway Meteorological Office Records: Thermo-hygrograph charts

Scope and Content

Thermo-hygrograph charts are a type of autographic record produced by a thermo-hygrograph machine that constantly registers temperature and humidity in a purpose made paper form wrapped around a drum.
They contain the original data that is registered in daily weather and observation registers (please see S81-Daily weather and observation registers).
Each sheet records half a week of data and they have a control header to note the latitude, longitude, the date the sheet was put on and removed from the thermo-hygrograph and the week number.

Administrative / Biographical History

The Isle of Man Meteorological Office (Ronaldsway Met Office) was opened by the UK Air Ministry as a method to support aviation, as part of a series of weather observation stations at Royal Air Force or Naval Stations throughout the United Kingdom.
The Isle of Man Met Office opened on 7th May 1946 in a barn southeast of Ronaldsway Airport. Some weeks later it was moved to the first floor of its control tower (which was demolished in 2012), starting its daily registers on the 24th July of the same year. In 2011 the office moved to Viscount House adjacent to the terminal building.
The weather readings were done manually, with an officer reading temperatures from the Stevenson screen on the airfield. These observations were completed at every hour of the day and night, 365 days a year and written observations were completed hourly until 1995, albeit with a gradual increase in technology as digital remote reading temperature sensors and laser cloud base recorders were introduced. Since 1995 the observations have still been completed, but are now printed via a computer rather than in ink on paper registers.
The Met Office, in administrative terms, moved from the Air Ministry to the Isle of Man Airports Board authority in 1965 and subsequently to the Isle of Man Department of Infrastructure, which allowed a closer relationship with the Island.
Today, the Island's Met Office has access to United Kingdom's Met Office computer weather models as well as information from other National Weather Services around the world, with forecasters at Ronaldsway interpreting the data to be used locally. These forecasts, observations and warnings are important for aviation, but also for the rest of the Island and users of its coastal waters. The forecasts are available via website, and by telephone with the information produced helping many people on a daily basis. Whether that is something simple like whether to wear a coat or hang the washing out today, the shipping companies to decide whether to sail or not, or for the emergency services and highways division to decide on response levels to a major flooding or storm event.


These records are arranged in the chronological original order they were created.

Access Information

For information on visiting the Isle of Man Public Record Office please see our website: .

Other Finding Aids

Please see our website for catalogues: .

Physical Characteristics and/or Technical Requirements

Records kept in their original envelopes. Each bundle contains 2 envelopes, 1 for temperature charts and the other for humidity charts.
There is presence of humidity damage in all records and they should be handled with care.

Archivist's Note

Catalogued by Liliana Silva, Records and Archive Officer, Isle of Man Public Record Office, May 2018

Conditions Governing Use

Crown copyright will exist in documents created by the United Kingdom and the Isle of Man Governments (duration - 125 years from the end of the calendar year of production)

Custodial History

The records in this series were stored at Ronaldsway Airport by the Isle of Man Met Office until they were transferred to the IOMPRO under section 3(4) of the Public Records Act 1999 on May 2017.


Accruals are expected to this series.

Related Material

  • S81 - Isle of Man Ronaldsway Meteorological Office Records: Daily weather and observations registers
  • S83 - Isle of Man Ronaldsway Meteorological Office Records: Barograph charts
  • S84 - Isle of Man Ronaldsway Meteorological Office Records: Thermo-hygrograph charts
  • S85 - Isle of Man Ronaldsway Meteorological Office Records: Rainfall charts
  • S86 - Isle of Man Ronaldsway Meteorological Office Records: Anemograph charts
  • S87 - Isle of Man Ronaldsway Meteorological Office Records: Monthly weather summaries