As open-source communities and other peer production projects face the challenge of sustaining themselves over time, the role of offline gatherings in fostering community resilience becomes a vital question. This study centres on the potential of offline social interactions as a means to mitigate declines within such communities, using Wikipedia as a case example. Using a comprehensive dataset spanning informal meetups within the German-language Wikipedia community from 2001 to 2020 and combining it with large scale online activity data, this study investigates the relationship between offline gatherings and online contribution behaviour. Results show that attending meetups has a positive effect on contributing towards Wikipedia both in the short and long term. By shedding light on the significance of offline social interactions in bolstering online communities, this study offers valuable insights into potential strategies for sustaining collaborative online environments amidst broader declines and further shows how offline and online activities intertwine.