Extremely hot temperatures have been linked to low soil moisture in southeastern Europe, but not in central Europe, finds an observation-based study online this week in Nature Geoscience. This shows that climate models correctly represent the relationship in southeastern Europe, but have overestimated the links in central Europe.

Martin Hirschi and colleagues analysed observational indices for soil moisture and temperature. They compared the relatively wet central European region with a dryer area in southeastern Europe and found that, whereas soil moisture affected the occurrence of extreme summer heat in the dryer regime, only a weak relationship was detected in the wet domain. Because soil moisture builds up over longer timescales, an impact of soil moisture deficits on extreme heatwaves could help with the development of early-warning systems.

In an accompanying News and Views, Lisa Alexander says “The study by Hirschi and colleagues [...] suggests that in some regions [...], prediction of the most severe events could be improved.”