Geological, geophysical and geochemical monitoring data provide the best insights we have into the status of a volcanic system. However, forecasts of the timing, location, size, and style of eruption based on these data are fundamentally uncertain. A statistical approach is required to work with them, and information useful to decision makers. Forecast uncertainty arises for a number of reasons.The physical and chemical processes controlling eruptive behaviour are inherently stochastic. Monitoring data is limited, ambiguous, and erroneous. Geological records are incomplete. And our models that relate changes in any of these to the likelihood, timing, and nature of future activity are wrong. Consequently,more reliable and useful quantitative forecasting will require developments in a range of statistical methods and understanding.This session is looking for contributions that address statistical issues in volcano monitoring and eruption forecasting. Topics could include: optimization of monitoring networks (for single volcanoes or across volcanic regions) to provide most useful forecasting information; approaches to deal with an absence of baseline monitoring data; forecasting changes in eruption style or the end of eruption; adjusting forecasts to account for missing data; the integration of ‘physics-based’ and empirical forecasting models; and tools to allow better decisions to made on the basis of uncertain forecasts.