Here’s a concise guide to — a weather injector/add-on for Lockheed Martin’s Prepar3D (v3/v4/v5) flight simulator. 1. What is P3DWX? P3DWX is a free, lightweight weather engine that downloads real-world METAR data and injects it into Prepar3D. It focuses on accurate real-world conditions with minimal performance impact, unlike complex payware (Active Sky, Rex Weather Force).