About Cumulus

From Cumulus Wiki
Revision as of 07:57, 22 March 2020 by Sfws (talk | contribs) (Web pages: add quote)

Cumulus is free software for retrieving, storing and displaying data from an electronic Automatic Weather Station (AWS). It offers a lot of features, here are the key ones:

Features of Cumulus Software

Key Features

  • Free for personal and non-profit use, but a donation would be appreciated if you continue to use Cumulus after trying it
  • Cumulus 1 runs on Windows XP, Windows Vista, Windows 7, Windows 8.1, and Windows 10
  • Supports Davis Vantage Pro and Pro2; Oregon Scientific WM918, WMR-918, WMR-928, WMR-968 weather stations; EasyWeather stations (MyDEL, Nevada, Watson, Fine Offset, WH1080, WH1081, W8681, FWS-20 etc); La Crosse WS-2300, and other models in the WS23xx range.
  • Easy to use, clean display (Cumulus 1 has display/editing screens appearing directly on PC running the software, Cumulus MX generates a user interface that is viewed (on your local network) using a browser)
  • Choice of meteorological day - midnight to midnight or 0900 to 0900 (optionally during summertime only 1000 to 1000)
  • Cumulus 1 offered real time web display of wind speed and direction using Silverlight software that is no longer functional
  • Automatic upload of data to web sites, Weather Underground, CWOP/APRS, PSW Weather/WeatherForYou/HAMweather, WOW, Twitter
  • Ready-made web template pages supplied, or build your own using web tags
  • Configurable alarms for various conditions
  • Sunrise, sunset, and (Cumulus 1 only) moon phase display
  • Cumulus 1 can display selected historical data for any given month, year, or other period
  • Cumulus MX saves data from past months and can output regularly to a database (either standard or customised)
  • Graphical display selected from Cumulus 1 main screen of historical data for any time period
  • Generation of xAP home automation weather reports
  • Comprehensive help file included
  • Free support available in the support forum

Special Features

  1. A key feature of Cumulus software, although only a minority of users utilise this feature, is its ability to mimic what many professional meteorologists do by starting a new meteorological day at 9am GMT (or your local time) with the option of either still using 9am in summer time (Daylight Saving Time - DST) or keeping to 9am GMT in summer by changing at 10am DST. This latter option preserves 24 hour long days even when the clocks change. Alternatively it can start each new day at midnight, and have shorter or longer days when the clocks change, this is the option that is slightly more popular.
  2. Another feature of Cumulus is that it can work with a number of different AWS, see suitable AWS list, most of these connect by a wire to the device that you are running Cumulus on. A side-effect of this is that it it tries to use as much common code that will work with various makes as possible, and is not specifically designed for, nor ideally suited to, any one make.
  3. Another key feature is that Cumulus reads the basic temperature, humidity, pressure, rain, and wind, readings from the AWS, but its outputs include many derived weather values.
    • Regardless of whether the AWS can calculate the highest and lowest values, Cumulus can (and for 9am to 9am if required),
    • it can combine the temperature it reads and the wind strength it reads to calculate current wind chill and also calculate the greatest wind chill in a day, month, year, or all-time,
    • it can also take into account humidity to calculate apparent temperature, Heat Index and Humidex values
    • Cumulus can count the hours when the temperature is below (adjustable) 7 degrees Celsius and total that for a season as Chill_Hours", you can tailor which month the count restarts each year.
    • It can track the number of degrees divergence and time for each divergence to calculate "Heat_Degree_Days" and "Cool_Degree_Days".
    • It can track the duration for each observed wind speed and calculate wind run for each day, it can report the day each month (or year, or all-time) with the highest daily wind run
    • Cumulus also tracks the actual rainfall over each 5 minutes and uses that to calculate a rain rate; it can report the highest hourly rainfall in a day, a month, a year or all-time; and it can report the wettest day in a month, year or all-time.
  4. Cumulus also includes a weather diary where you can record (in free text) any aspect of the weather for a day that your AWS does not capture, this diary includes ability to record for each day if snow is falling, if snow is lying, the snow depth, and from the last it can calculate a snow index for a month or for a winter.
  5. Cumulus also produces monthly reports summarising the weather each day of that month, and a yearly report summarising the weather each month of that year.
  6. Cumulus includes some templates that it processes to generate web pages, and provides hundreds of web tags that you can incorporate into templates of your own that Cumulus will process into scripts or web pages for you; there is a choice of how frequently this processing happens
  7. Cumulus also has the ability to launch external processes, at its "real-time" processing interval, its "normal updating" interval or as it is processing the daily "rollover" to a new meteorological day.


Two flavours of Cumulus are available for download from this page.

Cumulus 1

This is no longer developed and runs only on a device using the Windows operating system. There are large numbers of web sites (both private and public) using Cumulus 1 and it is probably the simplest version to install. However, there is no source available, and no author knowledge available (other than what appears at FAQ for Cumulus 1 and other pages in this Wiki.

The current stable version is 1.9.4 (28 November 2014). If you want to use it, download patch 2 (28 Jan 2020) as that patch has changed the drop down year selectors to allow selection of future years (to 2030) as well as past years. The non-patched version will accept any dates, but the drop-down selectors end run from 2000 to 2020 only.

Cumulus 2

This is no longer available as it never worked satisfactorily. Some of its features were incorporated into Cumulus 1.9.x and from there into Cumulus MX. Some other ideas like separating the engine and user interface formed the basis for Cumulus 3.

Cumulus 3 aka MX

Cumulus MX is newer, and still being actively developed, it will run on a number of operating systems and has the advantage that it consists of an engine that reads the AWS, does the calculations, and creates a web server. There is then a separate user interface that runs in this web server, and lets you see a number of dashboard type web pages and edit settings. This separate user interface can run on any device connected to your local network (LAN) or wifi, as it just just needs a private link to the device running MX. Despite MX being more complicated to get to know, it does offer more features and can connect to more AWS than Cumulus 1. This is not the place to list all extra features, but it can output to a database, it maintains its file of extremes for a month and year beyond the end of those periods, and adds the ability to process a file only at end of each day.

Outputs to external web sites

Cumulus will store full weather records, along with daily and all-time records, and graphical data. Cumulus can upload its data to a web server and comes packaged with template web pages for this purpose. Cumulus also supports automatic uploads to Weather Underground, PWS weather, Weatherbug, WOW and CWOP/APRS.

A variety of example screen shots are available for Cumulus 1, and those for MX will be added in the future.

Supported Devices

This varies between Cumulus 1 and MX.

There is a full list of Supported Devices

Web pages

Steve Loft once described the web pages he provides with Cumulus with these words: "They exist because they're our web pages, and they're really only included with Cumulus as examples of how the web tags work. It never occurred to me that most people would simply use the supplied examples instead of creating their own pages!"

Web pages included:

  • Current Conditions
  • Gauges (in Cumulus 1 with real time wind display, in MX using Steel Series dial representations)
  • Current Meteorological Day: Maxima and Minima
  • Previous Meteorological Day: Maxima and Minima
  • This month and this year: Maxima and Minima
  • Monthly Records: Maxima and Minima
  • All Time Records: Maxima and Minima
  • Trend Graphs

The standard menu navigation allows for inclusion of both a support forum link and a link to a webcam. Custom web pages can be achieved through the use of web tags added to any HTML/CSS layout.

Help and Support

Cumulus 1 includes a comprehensive Help File, this can be downloaded from here if you are using MX, but it is designed to be used on windows operating system.

There are pages within this Wiki contents page that discuss:

  • Frequently Asked Questions for Cumulus 1 (although it has some applicability to MX and does discuss weather station positioning; and a new one for Cumulus MX (only rough outline at present)
  • each of the configuration and log files,
  • list the web tags available, and how to use input and output parameters with them
  • give guidance for setting up a web site whether using the provided template pages, or ones you have edited/created, plus other "web tips"
  • some 3rd party apps and tools that can be run on your web site
  • weather terminology, explaining the various terms that Cumulus uses, the way that derivatives are calculated, and the ways that your weather station can measure what it reports to Cumulus

Further help, support, and discussion is available on our Forum. You will need to register to be able to post to the forum. Please submit bug reports and requests for enhancements there. You will find a guide to how to capture a what is on your screen in this wiki, as that can be useful when requesting support. You may also be asked to supply various files to help diagnose your problem. Do that by using Zip to compress all the requested files, then below the window where you post your response click on the tab labelled attachments for further instructions.

Donations & Sandaysoft

a note from the original developer...

Sandaysoft was the home of Cumulus, software to help you make the most of your weather station. When I wrote it I was located on the island of Sanday, in Orkney, off the north coast of Scotland in the UK. Cumulus is donationware. If you like the software and find it useful, please make a contribution towards the continuing development of Cumulus.

I rely on your donations to allow me to buy the software that I need to continue improving Cumulus. 100% of any donation received goes towards software development, either towards the cost of new development tools or the cost of hosting this site. I and my wife didn’t make a profit from Sandaysoft - when I was writing Cumulus 1, 2, and 3, I had a full-time job and Sandaysoft was one thing we did in our spare time.


Steve Loft