Journalists have integrated social networks in their professional routines. Social networks allow spreading content and interacting with the audience. However, in its role as an information source, they are controversial. Journalists oftn choose the immediacy of Twitter to get information. The aim of this paper is to analyze the content of tweets associated to hashtags to measure its potential as an information source of unexpected events. In order to do so, we have used a combination of quantitative and qualitative techniques of content analysis. We have studied the tweets linked to #ArdeValencia, a tag about the wildfires in July 2012 in Valencia (Spain), which burned 50000 hectares. The findings indicate that almost no scoop is disseminated. We detect little exclusive information. Nevertheless, it’s frequent to find reiterative comments, data and news previously published in the traditional media. From this perspective, Twitter’s role as an information source is doubtful, but it can work as an ambiental thermometer. In fact, about half of tweets criticize the Valencian Government, due to their budget cuts on wildfire prevention. Therefore, we note users use hashtags to take sides and express their ideology.