Along with fireworks, the start of Utah's Fourth of July weekend proved to be sizzling in a less welcome way Saturday, with hot weather keeping the region's waterways at flood levels as snowmelt accelerated.

High temperatures rose into the 90s in northern Utah on Saturday and are expected to top 100 degrees Sunday, expected to be the warmest day of the year so far, said National Weather Service meteorologist Monica Traphagan.

The state's southern reaches ranged from the upper 90s to low 100s Saturday — with a scorching encore forecast for Sunday.

The NWS, predicting clear and sunny skies throughout the weekend and into Independence Day, extended flood warnings for more than half a dozen rivers and creeks throughout northern and eastern Utah, though no serious, widespread flooding was expected, Traphagan said.

In Salt Lake County, Little Cottonwood Creek was near flood stage early Saturday and was projected to reach or exceed flood stage Sunday.

The upper Weber River near the Summit County town of Oakley was expected to remain at or over flood stage throughout the holiday weekend.

In Cache County, floodwatchers were closely monitoring both the Logan River, in the central part of the county, and Spring Creek, where it flows through the town of Providence.

Forecasters also issued flood warnings for the southern slopes of eastern Utah's Uinta Mountains. In particular, emergency services officials were concerned with spillage from the at-capacity Upper Stillwater Reservoir, which elevated flooding risks for both the Duchesne River and Rock Creek.

On Saturday afternoon, NWS added the Green River along its route through western Grand and eastern Emery counties, especially near the town of Jensen, to its flood warnings list.

remims@sltrib.com

Reporter Lindsay Whitehurst contributed to this story.