Yea. Tornado outbreaks in March and April are usually going to coincide with abnormal warmth and humidity for the time of year. That doesn't mean you need summer-like temperatures though. Shear is far more important, and low cloud bases / high relative humidity is very beneficial because evaporative cooling from nearby precip won't completely stabilize surface-based storm-inflow.
I think Dr. Leigh Orf's work provided some pretty strong evidence that violent tornadoes ingest a lot of surface-based parcels that are more stable than average, yet still realize some positive buoyancy once lifted into the middle levels of the storm by the upward vacuum-suction force of the rotating meso. Hot weather brings you the highest surface based CAPE, but that CAPE can be completely neutralized by just a little bit of precip if the boundary layer is characterized by low relative humidity. The result is many hot-day summer supercells have elevated inflow, and thus never produce tornadoes. Early spring supercells are very good at producing tornadoes because they often form in an environment where instability is more than adequate for strong convection despite high boundary layer relative humidity.
