A West Nile virus (WNV) introduction in Belgium in the near future is likely as neighboring countries report human and animal cases since several years. To support risk assessments, we determined the vector competence of Belgian Culex pipiens mosquitoes, considered to be an important WNV vector. Field-collected mosquitoes were offered a WNV-spiked (Israel 98, lineage 1) blood meal. Blood fed females were kept for 14 days at (i) a constant 25°C, (ii) a 25/15°C day-night gradient reflecting current Belgian summers or (iii) a 25/20°C day-night gradient simulating a climate change scenario. After the 14-day incubation period, abdomens, head/wings/legs, and saliva were collected and tested in RT-qPCR to determine infection rate (IR), dissemination rate (DR), and transmission rate (TR). Observed viral loads in the abdomen and IRs (29.6%, 33.3%, and 35.7%) did not significantly differ between temperature conditions, suggesting limited impact of temperature on virus replication in the gut. Interestingly, the DR at 25/15°C (88.2%) was statistically higher compared to DRs at both gradients (53.3% and 33.3%), indicating that WNV more easily passes the midgut barrier at the temperature condition reflecting current Belgian summers. The entry of WNV into the salivary glands did not seem to be altered by temperature, as no statistically significant differences were observed between the obtained TRs (50%, 30.8%, and 16.7% at 25°C, 25/15°C, and 25/20°C, respectively). Culex pipiens is thus a competent WNV vector at all three tested temperature conditions and will most likely play an important role in WNV spread upon an introduction in Belgium.