British household energy bills are forecast to rise by 13% from July, increasing annual costs for a typical dual-fuel household by 209 British pounds ($280) to 1,850 British pounds, Cornwall Insight analyst Craig Lowrey said in a note on Tuesday.
The forecast increase reflects a sharp rise in wholesale gas prices following US and Israeli missile strikes on Iran and subsequent retaliatory attacks that damaged Gulf energy infrastructure and disrupted shipping through the Strait of Hormuz, a key route for global oil and gas supplies.
"The main driver for the increase in our forecast is rising wholesale prices," Lowrey said.
Although a temporary ceasefire helped calm markets, prices remained elevated, pushing forecasts above current levels by more than 200 British pounds.
Lowrey said the summer increase would be less severe for households because energy demand typically falls in warmer months, but warned that October could pose a greater challenge if prices remain high as colder weather drives up consumption.
"If the cap stays at a similar level as July, that is when the Government will need to think seriously about targeted support for the most vulnerable," he said.
UK energy regulator, Ofgem, is consulting on lowering its benchmark for average household energy consumption to reflect declining usage levels. Cornwall Insight said this could reduce the headline "average bill" figure in future forecasts, though actual costs would still depend on household consumption because the cap limits unit rates rather than total bills.
Lowrey said Britain's reliance on imported LNG left consumers vulnerable to global price shocks and argued that expanding renewable energy capacity offered the best long-term path to greater price stability.