Yes, travel insurance is worth carrying for a trip to Ciudad Constitucion, and whale-watching season is the main reason most visitors pass through this inland Baja California Sur town at all. Magdalena Bay, reached from nearby Puerto San Carlos, draws travelers each winter for close-range gray whale encounters by small boat, and that activity, combined with the town's distance from a full hospital, is the honest core of why coverage matters here.
Ciudad Constitucion has basic local medical services, but anything serious is typically stabilized locally if possible and then transferred to La Paz, the state capital and the real regional medical hub, several hours away by road. Confirm your policy covers medical evacuation and inter-city transfer rather than assuming a routine clinic-visit benefit will be enough, since that road transfer is the part most likely to involve real distance and cost.
Whale-watching by small boat out of Puerto San Carlos, roughly the peak season running from January through March, is a genuine draw and a genuine activity risk - check that your policy covers boat excursions and does not treat wildlife-watching tours as an excluded activity, particularly if the trip involves a panga or similar small open vessel on open water.
Hurricane season on Mexico's Pacific coast, roughly June through November, can bring storms that affect Baja California Sur directly, disrupting flights, roads, and any coastal excursion around Magdalena Bay with little warning. Trip-delay and cancellation cover is worth checking closely if your visit falls within this window, since remote road access to Ciudad Constitucion can be affected by storm damage even after a hurricane has passed.
Keep any clinic paperwork, boat-operator incident reports, and receipts for treatment or transport if you need to file a claim, since documentation matters more in a remote town like this than it would in a major resort city. Check whether your existing health cover extends abroad and specifically to Mexico before relying on it for a whale-watching itinerary built around Ciudad Constitucion.