Japan’s day-ahead electricity prices have climbed to their highest level in three and a half years as extreme heat, soaring LNG costs, and a weaker yen combine to tighten the country’s power market.

Japan's import bill reached a record high in June as soaring oil prices forced the country to spend far more on energy while diversifying away from Middle Eastern suppliers.

Japan’s day-ahead electricity prices have climbed to their highest level in three and a half years as extreme heat, soaring LNG costs, and a weaker yen combine to tighten the…