Natural-gas prices are heating up ahead of air-conditioning season, adding pressure to household budgets and manufacturing costs. Futures for June delivery reached $9.399 per million British thermal units on Wednesday before ending at $8.971, up roughly 2% on the day and more than 20% this month. Prices have tripled over the past year and haven’t been so high since 2008, which was before frackers flooded the market with cheap shale gas . Continue reading your article with a WSJ membership View Membership Options