<p>Weather warnings serve the purpose of informing the public about potentially dangerous weather events so that they can take precautionary measures to avoid harm and damages. However, weather warning are often not user-oriented, which leads to poor understanding and low compliance rate. Moreover, warnings are often received during daily activities when the decision whether to respond to the warning might be taken within only a few seconds. The present study focuses on the question, which elements of a warning message are the most important to influence the spontaneous reaction to the warning and the intention to take action.</p><p>In a factorial survey experiment with 2000 Swiss citizen, we tested the influence of different elements of a warning message on people&#8217;s spontaneous appraisal of the warning and their intended behavioural change. The elements of the warning message we tested for were physical values (e.g. amount of rain in mm.), impact information, behavioural recommendations, warning level and labels for the severity of the event (e.g. &#8220;very severe&#8221;). We used an implicit association test to measure spontaneous appraisal of the warning message with respect to understanding, trust, risk perception and personal relevance. After the implicit association test, participants explicitly answered whether they would change their behaviour in response to the warning.</p><p>The experimental setup allows us to test for causal relations between the different elements of the warning message and the spontaneous reaction and intended behavioural response. Measuring the implicit associations provides us with a better understanding of the first reactions triggered by the warning elements and how that impacts intended behavior.</p><p>Our results (available by the end of April) will shed light on the question which information is the most important to serve as a wake-up call &#8211; a question that becomes even more relevant as warnings are increasingly transmitted via push-notifications on mobile phones. At the same time, our study provides a further insight into the cognitive process that underlies the decision to take protective actions.</p>