Data Logging and Software for Automatic Weather Stations


One of the major benefits now available with lower-cost, automatic weather stations such as the Davis systems is that the weather data can be processed automatically by computer and viewed on both local displays and on remote websites.

How far you take this process is very much up to you. Some users are content with simply keeping a comprehensive archive of their weather data on a PC for future reference. (NB We’re using ‘PC’ as shorthand for any type of compatible computer, including Macs, Linux machines etc, though there’s greater choice of software with a Windows PC.) Others may be more ambitious and take full advantage of the power that modern software and web servers provide to create visually impressive, real-time presentations of their weather data on web pages that may be viewed from anywhere in the world.

If you wish to use any of these PC or webpage-related features then you will typically need to add a data logger to the weather station itself. In the Davis architecture, for example, a Weatherlink data logger is essential to connect the weather station to a computer or network – you cannot connect the console unit direct to a PC. (We do have special bundles of station plus logger available throughout the Davis range, which offer a considerable discount on the logger list price.) Note that the Davis logger is a true data logger and can store data for extended periods, for example while you’re away on holiday, for later download to a PC.

And, even if you’re not a PC expert, it can be relatively simple to make your weather readings available to the world on a web page. The image below shows live weather readings (check the time and date) from our workshop location and is easily achieved by connecting a special Davis WeatherlinkIP data logger directly to your home network (no PC needed) and simply including the resulting image in your web page.

This image is an example of a presentation from the Davis Weatherlink Network. The same presentation can also be generated by using a Weatherlink v6 subscription (from software running on a Windows PC) or from a Vantage Connect unit, as used for weather monitoring at a remote, unattended location.

(Let’s be clear, you don’t have to connect a weather station to a PC – the built-in console display does provide a good snapshot of what the weather is doing right now, so if you’re allergic to PCs then you can still enjoy a lot of interest and value from a standalone weather station. But adding a data logger and PC connection to the system does add hugely to the station’s capabilities and so most customers nowadays do specify the logger option.)

This page provides a general introduction to the process and benefits of using data loggers with weather stations. There is also an introductory page specific to the standard Davis Weatherlink logger, which you may wish to read in addition.

In more detail

Davis Logger & Software Topics

Handling weather data on PCs & websites is covered extensively on this site – here are some links  to related PC and website topics (current page is shown unlinked):

Overview of loggers & software;
Advice on PC linking
Introduction to live weather websites
Advice on weather websites
Details of the Weatherlink product
Summary of compatible software;
Various advanced topics

This overall topic of data logging and software for our automatic weather stations is a large one. For readers interested in a full discussion, various topics are covered in different places on this website – see the box to the right for a guide on where to find the relevant pages.

However, the basics are very straightforward: The Davis weather stations range offers comprehensive data logging and interface features and there is a wide choice of compatible software to store, analyse and present your weather data, both locally and on web pages.

This present page, together with a couple of further pages linked to below, should provide all the introduction that new users will need. This section first summarises what’s possible with a modern data logger, followed by a brief description of the logger hardware and features and, in the final section below, a short introduction to weather station software. There is also an examples page that shows a number of illustrations of the diverse data presentations that can easily be created on local PC displays and on websites; and the WeatherlinkIP page has more detail on this special advanced data logger option.

The range of capabilities provided by a Davis Weatherlink logger includes:

  • Automatic long-term logging of detailed weather records, allowing high-resolution archives of weather data to accumulate over months and years. The logger will store data for extended periods before download to a computer is necessary;
  • Customisable (depending on software used) real-time displays of current weather conditions on PC (or Mac) monitors and large screens;
  • Analysis of logged data (eg to generate monthly summary reports) and graphical presentation of data on time-scales ranging from hours to months in visually impressive charts;
  • Any of the above three capabilities may be implemented using long distance data links and/or on websites;
  • Sending alarm messages (eg by email or SMS) and control of external electrical equipment such as heating and ventilating systems in response to changing weather conditions;

It’s perhaps worth adding that not all applications need sophisticated logging solutions as provided by the Davis and Instromet loggers – sometimes the requirement is just for the simplest, lowest-cost way of automatically logging a long-term record of basic weather readings such as wind conditions at an unattended site. Although most of the descriptions below exemplify reasonably high-tech logging and data handling solutions, we do also have loggers for the simpler applications such as the LeWL logger.

The Data Logger

6510_USBVP2console+loggerData loggers come in different shapes and sizes according to their maker and role. For the Davis stations, for example, the logger is typically a relatively small module that fits into a recess on the lower rear of the display console unit. (See close-up logger image left and installed into a VP2 console right.) Once installed, the logger effectively becomes part of the console. Some other standalone loggers such as the LeWL wind logger look quite different (see LeWL page).

Data loggers for most of the weather stations we sell can perform two distinct roles in generating archive data and real-time data. It’s worth appreciating the difference between these two roles because it makes understanding how best to use the loggers in different applications much clearer. (But don’t worry if this explanation isn’t crystal-clear at first sight – most logging configurations are relatively easy to set up and don’t necessarily require behind-the-scenes knowledge; the screen-shots on the examples page will quickly show the range of possibities):

  • Archive data logging (also termed true data logging): In this role the logger receives data either direct from the weather sensors or – more commonly – after initial processing of the raw weather data by the display console and then automatically stores summary values for the various weather sensor readings at preset intervals, for example every minute or 10 minutes or every hour. In this way, the data logger can accumulate a complete and detailed history of weather conditions over a period – potentially up to a week or a month or even more, depending on the type and capacity of the logger. This archive of summarised data remains stored in the data logger until it is connected to a computer and a program requests a download of the archive (which may be just a partial download, ie of any new data that has not previously been downloaded).
  • Real-time data feeds: The logger provides an interface to a PC which allows real-time data (ie readings refreshed every few seconds) to be accessed by programs running on the linked PC. It’s this type of data feed that will be used to provide real-time weather displays on PC monitors, websites etc. Typically, this real-time data is transient and not stored at all by the logger – ie if a linked PC is not listening in when the latest data refresh is available then that data record will be lost.

All Davis loggers are clever enough to be able to perform both of these roles simultaneously, if required to do so. But some of the simpler loggers, such as the LeWL logger, are only usually required to carry out the archive data role.

There can be a further twist to these archive/real-time roles. Some logging systems using third-party software programs are set up with a PC constantly switched on and listening to the real-time data. In these systems, it’s the PC program and not the logger that processes the real-time data stream and summarises it to generate the archive data. Not surprisingly, the format in which the archive data is stored on the PC’s hard drive will depend on the processing program being used.

Davis is somewhat unusual as a manufacturer of weather stations by providing a complete range of loggers with different features, all Davis loggers bearing the family name Weatherlink . Because the Davis logger is a separate part from the weather station console, this allows users to specify the station and logger types independently and thereby to tailor a PC-linked weather station system to meet their exact requirements.

The cheapest and most popular Weatherlink logger nowadays is the part with a USB interface (6510USB) to connect to a PC or laptop. A similar logger is also available with a serial/RS232 interface (6510SER), which some customers still prefer in certain circumstances. These two loggers are described on our main Weatherlink page.

In addition to the standard USB and serial Weatherlink loggers, there is also a set of advanced Davis data loggers, which offer important further features in addition to the archive and real-time data roles. Details of these can be found on the following specific product pages:

  • The WeatherlinkIP logger has a network (Ethernet) interface and has the key advantage that it can connect directly into a network access point or Internet router. In other words this IP logger (part 6555) does not need to be connected to a local PC to provide the simplest possible way of making your live weather data available worldwide on the Internet;
  • There is a set of four Streaming Weatherlink loggers that are customised for specific applications such as triggering hardware alarms;
  • The Vantage Connect unit is the ultimate in integration for remote weather monitoring. This unit combines the functionality of the WeatherlinkIP logger with a mobile phone modem and solar panel power supply. The resulting system can be placed in an open field literally anywhere that has mobile reception and will report back live data automatically to the central server at from where the data may be viewed in a standard web browser worldwide.

Also, for anyone to whom this might be of interest, we are able to source a Modbus interface to the standard Davis 6510SER serial logger – please see the page on Modbus Accessories for further details.

Weather station software

This section introduces software for weather stations that runs on a PC or similar  local computer. It assumes that the data logger will, typically, be cabled to a PC (or in the case the case of a logger with an Ethernet interface such as the WeatherlinkIP logger, cabled to a network access point with communications to the PC possible via the network).

Software running on the PC can then control a whole range of possible presentations of weather data, the three most common applications being a real-time graphical display of current weather conditions; a summary of the data over a period of time (eg a calendar month) in text or chart form; and managing an automatically-updating weather website on a remote web server.

The data feeds from a logger are often in a specialised data format and so it’s important that the software can decode the data as required – so compatibility with each particular type of logger is required. Typically, the data loggers cannot (but with certain exceptions) output in either plain text format or in complete web pages – a computer is generally needed to create the final display at some point between the logger and the display.

WL_packThe best-known program available for use with the Davis stations and loggers is Davis’s own Weatherlink program, which is supplied  as a standard part of the Weatherlink pack and so every logger purchaser also gets a ‘free’ copy of the Davis software – it is not necessary to specify software separately, unless you wish to use a third-party program. (‘Weatherlink’, perhaps a little confusingly, is the name used by Davis for the logger itself, their own processing program and also the standard pack containing both of these items.)

So many Davis VP-family stations have been sold worldwide since 2001 that an active market has developed in third-party programs that are compatible with the Davis loggers, with the result that there’s a wide choice of programs, including Weatherlink itself of course.

We’re often asked about which program is the best to use, but this isn’t an easy question to answer – each of the alternative programs to Weatherlink has its own features and pros and cons (summarised on our compatible software page and illustrated on the examples page) – and so it really depends on your own requirements and priorities. We generally recommend looking at the Weatherlink program itself to start with – you get a copy free with every Davis logger and it’s perhaps the most professionally produced and most widely used of all the programs. But it’s not as fully-featured as say Weather Display or Cumulus, nor is its real-time display as attractive as Weather Display Live or the SteelSeries gauges. Cumulus is attracting a lot of new users because of its balance of features, ease-of-use and clarity, plus it’s free to download.

Most Davis station owners run Windows on their PCs and so inevitably the great bulk of the Weatherlink and third-party program development has focused on Windows software versions. However, both the Weatherlink program and certain other programs are available in a Mac version and Linux versions of a few third-party programs are also starting to appear. If at all possible, we recommend using Windows software – simply because the vastly larger user-base of Windows versions means that these programs offer more features and flexibility. Read more about Windows vs Mac weather station software.

Continue to the examples page for software displays.