The National Weather Service has issued forecasts for a multi-day heat wave affecting more than half the country, with highs in the 90s to low 100s Fahrenheit and heat indices up to 115 F across the lower Great Lakes, mid-Atlantic, and Mississippi and Ohio River valleys. The period coincides with the July Fourth holiday and World Cup matches in several major cities. Additional weather hazards including thunderstorms, flooding, and fire conditions are noted in other regions.