Voltage and current were measured using a digital oscilloscope (WaveRunner 8254, Teledyne LeCroy). The voltage was applied for around 100 s, during which the temperature of the electrolyte increased, leading to higher current densities over time (see Section S2 in the SI). The experiment was then repeated in the heated electrolyte and with the electrodes in the same positions. Higher electrolyte temperatures have no measurable effect on the evolution of currents around plasma ignition. However, the ignition occurs earlier, as shown and discussed in Section S2 in the SI. The data presented in this work, exemplifying our approach, is from a second electrolysis cycle, where the electrolyte temperature is about 50 °C. A second data set supporting our data was recorded with the same experimental setup. However, images showing individual discharges were not recorded 1 s, but 1 min after ignition. The images in that video are less sharp. Overall, similar conclusions can be drawn from the results. The dataset and the subtle differences are shown in the Supporting Information Two (SI2).