Extreme Heat Warnings are in effect for portions of SW AZ and SE CA through Friday. The Yuma area and most of western Imperial County, including the Imperial Valley, will be under the warning through 8 pm MST/PDT Friday. The warning expands northward for the Lower Colorado River Valley and eastern Riverside County for just Thursday from 10am MST/PDT through 8pm MST/PDT. Afternoon highs are expected to peak upwards of 104°-108°F, around 10-15 degrees above normal for this time of year.