Online first-order monitoring is the task of detecting temporal patterns in streams of events carrying data. Considerable research has been devoted to scaling up monitoring using parallelization by partitioning events based on their data values and processing the partitions concurrently. To be effective, partitioning must account for the event stream’s statistics, e.g., the relative event frequencies, and these statistics may change rapidly. We develop the first parallel online first-order monitor capable of adapting to such changes. A central problem we solve is how to manage and exchange states between the parallel executing monitors. To this end, we develop state exchange operations and prove their correctness. Moreover, we extend the implementation of the MonPoly monitoring tool with these operations, thereby supporting parallel adaptive monitoring, and show empirically that adaptation can yield an up to 8.9-times improvement in run-time.