A quality-controlled data service of volunteered weather observations

Air temperature over Utrecht province during a heat wave in 2018 as measured by WOW-NL

In 2011, the UK Met Office launched a citizen science project intended to collect data from citizen weather stations (CWS) and, to date, the Weather Observations Website (WOW) project has collected over 1,400 million observations worldwide collected by over 17,000 CWS. The Dutch Met Office (KNMI) joined this project as a partner in 2015 and currently, 500+ CWS monitor the weather in the Netherlands producing over 2 million volunteered weather observations per month. The WOW-NL network represents the KNMI contribution to WOW and includes a WOW-NL website. In March 2019, we started exploring and assessing this vast collection of volunteered weather observations from WOW-NL. Our main goals are:

  • Assessing the quality of CWS observations
  • Exploring how to create a data service providing CWS observations
  • Exploring innovative uses for CWS observations

Assessing the quality of WOW-NL observations

The WOW-NL CWS take measurements for several weather variables, such as temperature, precipitation, or wind speed. The CWS in the WOW-NL network are semi-professional devices capable of measuring weather with a reasonable quality. However, since these devices might be placed in urban settings, local cooling, shadowing, or radiative effects can influence the measurements taken. Starting with temperature, we implemented the quality control (QC) procedure described in (Napoly et al., 2018). Our results (check slides below) show that:

  1. Most of the stations have a sufficient coverage and the observations are strongly correlated
  2. Over half of volunteered observations per year have a sufficient quality compared to official measurements

Next steps include extending the QC assessment to other variables, such as wind or precipitation.

Creating a cloud-based quality-controlled data service

In April 2020, we got an Amazon Web Services research grant to investigate how to create a data service providing quality-controlled observations from WOW-NL. The idea is to use several AWS technologies and services to create a repository in which each WOW-NL observation is annotated with different quality levels for each of the monitored variables. Once this repository is created, we can enable querying and analytical capabilities in the cloud, so users can incorporate these observations into their modelling or visualization workflows.

Exploring innovative uses for CWS observations

Recently, researchers in the climate science are assessing the potential of crowdsourced weather data to improve the weather forecast (Hintz et al., 2018). The volume of observations produced by the WOW-NL network presents a great opportunity to assess whether volunteered observations can improve the numerical weather prediction.

Additional information

  • Funding: KNMI
  • Duration: Mar 2019 - Present
  • Status: Ongoing, check later this year for updates.


  • Napoly A, Grassmann T, Meier F and Fenner D (2018). Development and Application of a Statistically-Based Quality Control for Crowdsourced Air Temperature Data. Front. Earth Sci. 6:118. doi: 10.3389/feart.2018.00118

  • Hintz, KS, O’Boyle, K, Dance, SL, et al. Collecting and utilising crowdsourced data for numerical weather prediction: Propositions from the meeting held in Copenhagen, 4–5 December 2018. Atmos Sci Lett. 2019; 20:e921. https://doi.org/10.1002/asl.921

Irene Garcia-Marti
Irene Garcia-Marti
PhD Data Scientist

I have a keen interest in applying machine learning methods in the field of spatio-temporal analytics.