Summers in Utah are scorching, with the average high temperatures in the range of 85°F (29.4°C) to 100°F (37.8°C) at the peak of July. The dryness results in low humidity and significant temperature variations keep the nights cool in the summer, especially in the high mountains.
Weather in June
June begins the hot summer season in Utah, with the sun rays gradually rising in intensity. The wilderness and natural beauty of the state draw tourists from distant lands. The average high temperatures are between 63°F (17.2°C) to 96°F (35.6°C), while the average low temperatures are in the 38°F (3.3°C) to 67°F (19.4°C) zone. Green River in the south registers comfortably warm average temperatures in the 55°F (12.8°C) to 93°F (33.9°C) zone.
Humidity levels are low, particularly in the arid west, and the skies remain clear during the night. Moderate rain to the tune of 1 to 2" (50.8mm) accumulates in June. Thunderstorms are frequent in the afternoon, and tornadoes make an unexpected visit to Utah. A cloudburst can bring heavy rain in the span of a few hours and result in flash floods due to the inability of the soil and vegetation to hold any water.
June sees the tourist season at its peak in Utah, with the temperatures still bearable during the days and comfortable in the nights.
Weather in July
July is usually the hottest month of the year in Utah, with blistering sunshine that scorches the land. The average high temperatures are in the hot 72°F (22.2°C) to 101°F (38.3°C) range, and many places remain over 100°F (37.8°C) for extended periods. Summer nights are surprisingly comfortable with average temperatures in the 46°F (7.8°C) to 75°F (23.9°C) zone.
Tourist footfall is on a high in Zion National Park in the west, even though the temperatures are in the hot 69°F (20.6°C) to 101°F (38.3°C) range. Camping grounds and mountain lodges scarcely remain vacant as camping, fishing, biking, and trailing gain momentum. Mountains and canyons are cooler by up to 20°F (-6.7°C) than the surrounding lands.
Rainfall is scarce, and the atmosphere is dry, with the average humidity below 50 percent. Brilliant sunshine makes light summer clothing with full sleeves and broad-brimmed hats the best way to combat the sun. Mornings are the best periods for outdoor trips during the day. Evenings have plenty of daylight and lots of fun activities in Utah in July.
Weather in August
August is a hot summer month in Utah, with the sun working overtime over the land. The average high temperatures are in the hot 70°F (21.1°C) to 99°F (37.2°C) range, while nights register between a moderate 45°F (7.2°C) to 73°F (22.8°C).
Rain is negligible as the summer retains a dry atmosphere with clear skies. The plains, as well as arid lands, are exceedingly hot, but the canyons, foothills and high mountain slopes experience different microclimates with cool nights. Camping under the open skies is marvelous for gazing millions of stars in the vast open sky. Float down the Provo River when the heat becomes unbearable for extended periods. Consider a backpacking trip to one of the many alpine lakes in the state for a rousing adventure.
Light summer clothing is ideal in August, with a light sweater for the night. The temperatures drop steadily with each passing that brings the end of the long summer. Keep an eye on wildfires and thunderstorms in the dry season in August in Utah.