Zambretti Forecaster

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The Zambretti Forecaster

The Zambretti Forecaster is a weather forecasting instrument used in conjunction with a barometer. It interprets the reading of a barometer into one forecast from a large selection of permutations after making allowances for variable factors. These include wind direction, a rising, falling or steady barometer, and the season.[1]

Negretti and Zambra were scientific instrument makers, noted for their barometers. The Forecaster was produced in 1915 as a portable forecaster which needed minimal instrumentation, a simple barometer and an observation of the wind direction, and was easy to calculate with. It was produced as a small disc calculator made of overlaid discs of ivorine, an early plastic.[2] Despite its simplicity, it achieved 90% accuracy for 12 hour forecasts.[2] The original Zambretti algorithm has since been implemented in a number of electronic forecasters.[1]


  1. ^ a b "Zambretti Algorithm". Meteor Metrics. Archived from the original on 2011-06-10.
  2. ^ a b "Zambretti Forecaster". Whitby Weather.