• Gerrit Hiemstra, MSc

    Co-founder and Chief Executive Officer

    Gerrit is a meteorologist with in-depth experience in the meteorological field. He graduated in 1986 at Wageningen University as Agricultural Engineer, with a specialisation in Agricultural Meteorology, followed by a 9-year period as operational weather forecaster in a commercial weather company.

    After a brief period as head of the operational weather service at Schiphol Airport he founded the successful commercial weather company WeerOnline, which was sold in 2009.

    Gerrit is also the well-known weather presenter of NOS, the national news organisation of the Netherlands, since 1998.

    At Weather Impact Gerrit is responsible for project acquisition and contract management.

  • Arnold Lobbrecht, PhD

    Co-founder and Chief Technology Officer

    Arnold graduated in 1986 from Delft University of Technology as Civil Engineer. He gained experience in hydrology, water management and informatics during a 12-years period at a multinational consultancy firm.

    After 4 years of research he obtained in 1997 his PhD in operational water management. After that he became part-time professor of hydroinformatics at UNESCO-IHE in Delft, guiding a group of PhD researchers. In 2000 he established HydroLogic, a hydroinformatics company, working on water & ICT projects.

    His experience is in decision support systems with focus on flood forecasting, water availability and droughts.

  • Stefan Ligtenberg, PhD

    Project leader and consultant

    Dr. Stefan Ligtenberg works at Weather Impact as project leader and consultant.

    Stefan graduated in 2009 at Wageningen University in Meteorology and Air Quality. He finished his PhD in 2014 on the field of polar meteorology at Utrecht University. Subsequently he started two postdoctoral positions at Utrecht University, for the last he received an NWO VENI scholarship.

    At Weather Impact, Stefan works as consultant and project leader. He has experience with weather forecasting in Southeast Asia and East Africa. He is an expert in translating meteorological weather parameters in messages that fit the local context of a farmer.

  • Bob Ammerlaan, MSc


    Bob Ammerlaan MSc. works at Weather Impact as consultant.

    Bob has a background in Physics and Meteorology and graduated in 2018 at Utrecht University in Meteorology, Physical Oceanography and Climate.

    At Weather Impact, Bob works as consultant meteorology and climate change. He is responsible for the operational services at Weather Impact. He has experience with weather forecasting in Southeast Asia and East Africa and is an expert in using agricultural and meteorological information to give the best advice to local farmers.

  • Edith Tea, MSc

    Business Developer

    Edith has studied Hydrology at Vrije Universiteit Amsterdam, for which she received a Rotary Grant Scholarship. She also has a background in Physics from Gettysburg College, United States. She has gained experience with proposal writing, academic research and has great skills in data analysis. At Weather Impact, Edith is responsible for project acquisition regarding weather services. She also speaks several languages – French, Spanish and English -, a great benefit for our international work.

  • Janina Fraas, MSc


    Janina holds a MSc Climate Studies degree at Wageningen University where she focused on meteorology and programming. She got to know Weather Impact already during her first year of the MSc studies where she worked on a university group project for Weather Impact. This project has inspired her so that she tailored her study program towards agro-meteorological climate services. Next to that, she brings an unique background because she holds a BSc degree in International Development Studies and took leading roles in several international student associations. At Weather Impact she works as consultant.

  • Tamara Lancel

    Management Assistant

    Tamara Lancel works at Weather Impact as Management Assistant.

    She graduated in Hotel & Hospitalitymanagement in 2007 and has a background in the hospitality industry, organizing congresses and events. In her last job she worked as a training coordinator and arranged technical IT trainings for the Benelux and Africa region. Tamara is very strong in planning, coordinating and organizing, and has experience in broad administrative and logistic work. At Weather Impact she supports the team in marketing, HR, administration, acquisition and other organizational tasks, to share our expertise about smart weather solutions.


  • Glenn van Graafeiland


    Glenn is finishing his master Climate Studies at Wageningen University. Before he did a bachelor Earth Sciences in Utrecht, where he graduated on surface water contamination. During his masters he discovered meteorology and was fascinated by this discipline. Glenn’s thesis consisted of an analysis of data gathered during the MOSAiC project, measured in the central Arctic. He has a lot of experience with data analyses techniques and is eager to make an actual impact on the challenges we face due to climate change. For this current internship he is involved in the Rain in Africa project, for which he will validate model output by means of observations by the Rwanda Meteorological Agency. Glenn will also look for potential customers and ways to disseminate the rainfall forecasts.