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A multi API consuming weather forecasting superstar.

Barometer provides a common public API to one or more weather services (APIs) of your choice. Weather services can co-exist to retrieve extensive information, or they can be used in a hierarchical configuration where lower preferred weather services are only used if previous services are unavailable.

Barometer handles all conversions of the supplied query, so that the same query can be used for all (or most) services, even if they don't support the query directly. See the “Query” section for more information on this.


Version 0.7.3 is the current release of this gem. The gem is available from gemcutter (barometer: Older version are available through rubyforge (barometer) and github (attack-barometer). It is fully functional (for five weather service APIs).


Currently this project has completed initial development and will work for a few weather services (wunderground, google, yahoo,, weather_bug). Barometer is developed using only Ruby 1.9.2, but will probably on both Ruby 1.8.7 and 1.9.1.

Features to be added in the future:

  • better command line output

  • even more weather service drivers (hamweather)

  • icon support


Google API key [UPDATED]

As stated on the Google Geocoding API website (, Google no longer requires an API key. Therefore Barometer no longer requires a Google API key.

other keys

The '~/.barometer' file can hold all your weather service API keys.





eg. Yahoo! Placemaker

  app_id: YOUR_APP_ID


Why? HTTParty was created and designed specifically for consuming web services. I choose to use this over using the Net::HTTP library directly to allow for faster development of this project.

It is possible that I will use Net::HTTP in the future.


Why? Barometer deals with time information for locations all over the world. This information doesn't mean that much if it can't be converted to times that don't correspond to the applicable timezone. Tzinfo handles this time zone manipulation.


The query handling is one of the most beneficial and powerful features of Barometer. Every weather service accepts a different set of possible queries, so it usually is the case that the same query can only be used for a couple weather services.

Barometer will allow the use of all query formats for all services (mostly). It does this by first determining the original query format, then converting the query to a compatible format for each specific weather service.

For example, Yahoo! only accepts US Zip Code or ID. With Barometer you can query Yahoo! with a simple location (ie: Paris) or even an Airport code (ICAO) and it will return the weather as expected.

acceptable formats

  • zipcode

  • icao (international airport code)

  • coordinates (latitude and longitude)

  • postal code

  • ID

  • location name (ie address, city, state, landmark, etc.)

  • woeid (where on earth id, by Yahoo!)

  • if the query is of the formats zipcode or postal code it may not support conversion to other formats.

conversion caching

Barometer has internal conversion caching. No conversion will be repeated during a measurement, thus limiting the number of web queries needed.

Example: If you configure Barometer to use both Yahoo and, then use a query like “denver”, this will require a conversion from “denver” to its weather_id. This conversion is needed for both web services but will only happen once and be cached.


You can use barometer right out of the box, as it is configured to use one register-less (no API key required) international weather service (

require 'barometer'

barometer ="Paris")
weather = barometer.measure

puts weather.current.temperature


The available sources are: (:wunderground) [default]
Yahoo! Weather (:yahoo)
Google Weather (:google) (:weather_dot_com) [requires key] (:weather_bug) [requires key]

source configuration

Barometer can be configured to use multiple weather service APIs (either in a primary/failover config or in parallel). Each weather service can also have its own config.

Weather services in parallel

Barometer.config = { 1 => [:yahoo, :google] }

Weather services in primary/failover

Barometer.config = { 1 => [:yahoo], 2 => :wunderground }

Weather services, one with some configuration. In this case we are setting a weight value, this weight is respected when calculating averages.

Barometer.config = { 1 => [{:wunderground => {:weight => 2}}, :google] }

Weather services, one with keys.

Barometer.config = { 1 => [:yahoo, {:weather_dot_com => {:keys => {:partner => PARTNER_KEY, :license => LICENSE_KEY } }}] }

multiple weather API, with hierarchy

require 'barometer'

# use yahoo and google, if they both fail, use wunderground
Barometer.config = { 1 => [:yahoo, :google], 2 => :wunderground }

barometer ="Paris")
weather = barometer.measure

puts weather.current.temperture

command line

You can use barometer from the command line.

# barometer berlin

This will output the weather information for the given query. See the help for more command line information.

# barometer -h


What would cause a weather service to fail? The most obvious is that the particular weather service in currently unavailable or not reachable. Other possible reasons would include not having the API (or a valid API key for the particular weather service, if required), not providing a valid query, or providing a query for a location not supported by the weather service.

For example, if you look at the example above, the query of “Paris” refers to a city in France. Yahoo weather services only supports weather results for USA (at least at the time of writing). Therefore, Barometer would not use Yahoo, just Google and failover to use Wunderground (if needed).


After you have measured the data, Barometer provides several methods to help you get the data you are after. All examples assume you already have measured the data as shown in the above examples.

by preference (default service)

weather.default         # returns measurement for default source
weather.current         # returns current_measurement for default             # returns current_measurement for default
weather.forecast        # returns all forecast_measurements for default           # returns forecast_measurement for default today
weather.tomorrow        # returns forecast_measurement for default tomorrow

puts weather.tomorrow.high.c

by source

weather.source(:wunderground)   # returns measurement for specified source
weather.sources                 # lists all successful sources

puts weather.source(:wunderground).current.temperature.c

by date

# note, the date is the date of the locations weather, not the date of the
# user measuring the weather
date = Date.parse("01-01-2009")
weather.for(date)       # returns forecast_measurement for default on date 
weather.source(:wunderground).for(date)   # same as above but specific source

puts weather.source(:wunderground).for(date).high.c

by time

# note, the time is the time of the locations weather, not the time of the
# user measuring the weather
time = Time.parse("13:00 01-01-2009")
weather.for(time)       # returns forecast_measurement for default at time 
weather.source(:wunderground).for(time)   # same as above but specific source

puts weather.source(:wunderground).for(time).low.f


If you consume more then one weather service, Barometer can provide averages for the values (currently only for the 'current' values and not the forecasted values).

require 'barometer'

Barometer.google_geocode_key = "THE_GOOGLE_API_KEY"
# use yahoo and wunderground
Barometer.config = { 1 => [:yahoo, :wunderground] }

barometer ="90210")
weather = barometer.measure

puts weather.temperture

This will calculate the average temperature as given by :yahoo and :wunderground


You can weight the values from a weather service so that the values from that web service have more influence then other values. The weights are set in the config … see the config section

simple answers

After you have measured the data, Barometer provides several “simple answer” methods to help you get answers to some basic questions. All examples assume you already have measured the data as shown in the above examples.

All of these questions are ultimately specific to the weather source(s) you are configured to use. All sources that have successfully measured data will be asked, but if there is no data that can answer the question then there will be no answer.

is it windy?

# 1st parameter is the threshold wind speed for being windy
# 2nd parameter is the utc_time for which you want to know the answer,
#   this defaults to the current time
# NOTE: in my example the values are metric, so the threshold is 10 kph


is it wet?

# 1st parameter is the threshold pop (%) for being wet
# 2nd parameter is the utc_time for which you want to know the answer,
#   this defaults to the current time
# NOTE: in my example the threshold is 50 %


is it sunny?

# 1st parameter is the utc_time for which you want to know the answer,
#   this defaults to the current time


is it day?

# 1st parameter is the utc_time for which you want to know the answer,
#   this defaults to the current time

is it night?

# 1st parameter is the utc_time for which you want to know the answer,
#   this defaults to the current time



  • create a Barometer instance

  • supply a query, there are very little restrictions on the format:

    • city, country, specific address (basically anything Google will geocode)

    • US zip code (skips conversion if weather service accepts this directly)

    • postal code (skips conversion if weather service accepts this directly)

    • latitude and longitude (skips conversion if weather service accepts this directly)

    • weather id (even if the service you are using doesn't use it)

    • international airport code (skips conversion if weather service accepts this directly)

  • determine which weather services will be queried (one or multiple)

  • if query conversion required for specific weather service, convert the query

  • query the weather services

  • save the data

  • repeat weather service queries as needed


Barometer attempts to be a common API to any weather service API. I have included several weather service 'drivers', but I know there are many more available. Please use the provided ones as examples to create more.


Barometer now uses 'bundler'. You just need to 'git clone' the repo and 'bundle install'.


Thank you to these developers who have contributed. No contribution is too small.



Copyright © 2009-2011 Mark G. See LICENSE for details.

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