Global natural gas prices edged upward despite limited activity on the market as traders weighed the potential winter supply risk from a widening war in the Middle East and colder forecasts.

European and East Asian benchmark prices jumped Monday, reversing last week’s downward slope as hefty storage levels and mild weather continued to drag on demand. The rise followed news that a Japanese-owned vessel had been seized by possible Houthi rebels off the coast of Yemen, stoking anxiety that the war between Israel and Hamas could be increasing risk for ships crossing one of the world’s critical energy routes.

Analysts with trading firm Energi Danmark wrote that market anxiety over conflict in the Middle East had previously appeared to be waning and the “risk premium is therefore...