Sharp price spikes are likely to continue this winter for natural gas delivered to Washington state’s Sumas hub, reflecting a market plagued by deficient infrastructure struggling to keep up with widespread demand growth in the West, according to traders and analysts.

Located on the Washington State border with British Columbia (BC), Canada, the Sumas hub serves as one of two main entry points for Western Canadian gas to flow into the U.S. Pacific Northwest. Kingsgate, near the Idaho border, is the other.

With little local natural gas production, the Pacific Northwest largely relies on imported supply to serve demand. Rockies natural gas supply is transported into the region during the summer, but come winter, it has to rely on Canadian imports as the Rockies holds onto its...