July is the beginning of the wet season in the Northern Mariana Islands that sees up to 10.2" (259mm) of rain. The average temperatures are in the warm 75°F (23.9°C) to 84°F (28.9°C) range. However, the increased cloud cover and humidity raise the heat index. It rains almost every day, but the showers rarely last for extended periods, and there is no shortage of sunshine. The hill paths become slippery and muddy and treacherous to ascend. Trade winds lose strength as clouds dominate the skies, especially during the afternoons. Sea temperatures are at the highest of the year, yet the waters are mild and suitable for water activities. The longest days of the year ensure there is plenty of daylight during the evenings for fun-filled activities. Thunderstorms are frequent with occasional lightning and heavy rain. Watch out for storms as the typhoon season begins in July in the Northern Mariana Islands.