Recent National Weather Service model runs and ensemble guidance point to a high near 86–88°F for Houston on May 19, driven by building high pressure and modest southerly flow that favors diurnal heating under partly to mostly sunny skies. Typical May climatology places the normal high at 88°F, while current moisture levels and a modest chance of afternoon convection could cap the maximum slightly below that benchmark or allow a brief push into the low 90s if clouds remain limited. The tight clustering of market probabilities around 86–89°F reflects this narrow forecast spread, with traders weighing the balance between expected surface heating rates and any last-minute adjustments to boundary-layer moisture or timing of sea-breeze development.