The National Weather Service says a potential record-breaking heat wave will impact Lake and Mendocino counties this week. By Wednesday, temperatures will climb into the 90s and 100s. The heat risk is forecast to be moderate with areas of high heat risk for interior Mendocino and Lake Counties Thursday and Friday, where highs in Lakeport and Ukiah will be between 105-110 degrees. The hot weather will likely persist next weekend, but temperatures should start to trend downward.