DMI forecast API for atmosphere, ocean and sea ice, free !

Updated 2024-02-10

DMI is the Danish Meteorological Institute and the Open Data API provides free and open access to DMI’s data.They are covering a pretty big area not just Denmark.

I'm maintaining the weather station for Domstens yacht club and have become really interested in weather "issues".

The actual use case for me is that I have to change the mooring, of our boat, if the water level exceeds 60 cm from normal. For several years I have been searching for a free forecast API so I can get an early warning when the water level rises.

Node-Red is used.

GRIB files and extracting data, Linux, Raspberry

Updated 2024-02-08

GRIB is a data format, used for meteorology, to store historical and forecast weather data. 

The use case for me was analyzing forecast data, from GRIB files, so an early warning could be rised before a high water level or coming storm appears. This could then be used at our weather site.

There are several applications, also ones that visualizes the data, but this post will handle how to extract data from files using command line.

Install Weather34 with WeatherLink, v2 API

Updated 2024-01-08 OK with Bookworm 64 bit, PHP 8.2 !

This post is an update from a former post which handles on how to set up a weather WEB-site with data from Davis Weather Link(WL) but here adapted to the latest WL API v2.

Any product that reports weather data to WL can be used as a source for this weather template.

This is made without additional software such as Cumulus, Weather display or the Meteobridge product.

RPi install Apache/PHP WEB-server

Updated 2024-01-07 ! OK with Bookworm & PHP 8.2 !

As a part of one of my project, the ultimate Weather site ? Weather34, I needed a WEB-host with PHP.

I started up with a fresh Raspberry OS Lite SD Card with Samba installed.

Log on, with ssh/terminal to the RaspberryPi(RPi), in this case hostname "pws01", and update the OS with

sudo apt update
sudo apt full-upgrade -y
sudo apt clean

go on and install the Apache server with

sudo apt install apache2

Install Weather34 with WeatherLink

Updated 2023-04-14 !! OK with Bullseye and PHP 8.x !

If You want Your Private Weather Station(PWS) Davis Vantage Pro2, or other Davis products that use WeatherLink, to provide data for the template we use at Domstens Båtklubb just follow the instructions below. 

This is made without additional software such as Cumulus, Weather display or the Meteobridge product.

This application is updated !!, to use the v2 API. Check  this post !!

Calculate wind using U and V GRIB components, NodeRed, JS

Updated 2022-11-28 !

In a former post I showed how to download and extract data from forecast GRIB files but avoided to handle if the wind direction and speed was declared as U and V components, vectors. 

In this post I will extract wind data from a GRIB forecast file and use the U V components to calculate, and display, wind speed and direction at a chosen point. The data is visualized as graphs in a NodeRed dashboard.

Normally, using charts in NodeRed, the timestamp is taken from the time when the input message is created but here I will use the timestamp from the forecast, loading the whole chart in one go.

Davis PWS linked to pwsweather.com

If you are using Davis Personal/Professional weather stations(PWS) you will get a nice dashboard when you link your PWS to the Davis weatherlink(WL) site.

What you probably really miss is a forecast displayed together with your PWS data. The picture is showing a part of the dashboard at pwsweather.com(PW) after you have linked your PWS to the site.

An add on is that you via API:s can get both the current weather, forecast and other data free of charge, via the aerisweather.com(AW) site.

This post will handle the setup and also a Node-Red dashboard interfacing the aeris API.

WeatherLink weather template, v2 API

I have written a post with the same subject before, also using NodeRed(NR), but this post is using the latest WeatherLink v2 API instead of the v1 API. 

The v2 API supports more devices and now also including the old ones.

If You want a more advanced weather site this is a very nice one coded in PHP also using the v2 API.

Davis weather station, WeatherLink, PHP

Updated 2021-12-05 !

In the harbour we are using a Davis weather station, Vantage Pro2, as our PWS(Private Weather Station).

If you like to display the data, online on the web, you can use the Davis service, Weatherlink(WL) where you register an account. 

Another way is to retrieve the weather data as XML or JSON, from the Weatherlink web-site, and use it in your own application (open source!).

Another approach with NodeRed could be find here.

SIGNL4, automated alerting with free mobile app

I'm involved in several projects where you, as quick as possible, want to get an alert if anything fails. After a lot of Googling I found SIGNL4.

They have several ways to create an alert, can involve a team, have a nice app and is free, up to 5 users, if you use the "STARTER" option.

In this post, as an example, I will show how I detect if my AIS receiver/dispatcher stops receiving AIS targets, sent to Vesselfinder, and how an alert is forwarded to the SIGNL4 app.

I'm using NodeRed on a Raspberry Pi to realize the function

WeatherLink weather template

Updated 2022-02-21 !

If You are interested in building Your own weathersite with information from Davis Weatherlink(DWL), and don't are a skilled programmer I can really recommend Node-Red(NR). In this post I give an example how to start with the NR dashboard GUI and DWL V1 API.

!! Please note new version with the latest v2 API !!

If You want a more advanced weather site/template this is a very nice one coded in PHP.

HomeKit with "ANY" temperature source

From AppleWatch

As long as it's possible to retrieve information, in some way, from a sensor OR a website/webserver, with temperature information, it's possible to show it in HomeKit with HomeBridge(HB).

In this post NodeRed(NR) is retrieving the temperature from Your selected source and is also acting as the WEB endpoint for the HB  "homebridge-http-temperature" plugin.

In my case I wanted an outside temperature so used the measurements from our Davis Weather station and their JSON REST API but it could for example be Your Raspberry CPU temp or showing the speed of Your Internet connection.

Weather34 & WeatherLink w/o cronjob

Running Weather 34, W34, using my setup, the program "cumulusdata.php" is fetching data from Davis Weatherlink(WL), and are writing the data to a file, type Cumulus. The old way was to fetch the data via a scheduled cronjob. 

Doing a small change to "windspeeddirection.php", "updater.php" , and using the latest version of "cumulusdata.php", will do the update with the built in W34 refresh routine instead of cron job.

Thanks to Ken who gave me the hint.

Mac install Apache/PHP WEB-server

Updated 2019-01-07 

!! Note !! Before Monterey !! 

As a part of one of my projects, the ultimate Weather site ?? Weather34(W34), I needed a WEB-host with PHP and started to use a Raspberry Pi.

In this post You will get some short install tips on Apache with PHP on a Mac with Mojave, macOS 10.14.x, and at the end of the post the W34 installation is done.

Weather34 install at WEB hotel

Updated 2019-04-01 !

Prerequisites is listed in the beginning of the post for installation on Raspberry Pi(RPi)

You will find migration information, from WeatherLink 1.0 to WeatherLink 2.0, in this post

Davis WeatherLink upgrade to 2.0

During summer 2018 Davis are updating WeatherLink to 2.0 (WL2). So if You have registered devices before 2017-11-28 You must migrate.

This update is changing their website, as shown in picture, and API.

Their API documentation is found here

The following information is sent out in 2018-06 to users who still haven't upgraded to WL2

Weather34, the production version

Updated 2019-05-12 !

I have got some questions which version we are using for the moment at the site vader.domsten.nu 

The version is from 2019-05-12 and You can get the whole site code from here.

Please note that I have done some modifications so if You want the original code please rename 

menu.php

The ULTIMATE Weather WEB-site ??

Updated 2017-08-25 !


If You have a Private Weather Station(PWS) and would like to have a good view over the data and, as an add on, also forecasts from Weather Underground (WU) this free software probably solves Your problem. Despite that the project is terminated the code is available and instructions is available at my other posts

https://weather34.com/homeweatherstation/