Why is the 2018 lava still so hot?

Two HVO geologists document road cutting activities on HWY 132 on August 7, 2019. One geologist is taking visual photographs while another geologist is taking thermal photographs to make a tandem pair for comparison. The temperature of the solidified lava was measured to 425 ° C (800 ° F) at the digging site. Photograph by USGS geologist K. Mulliken.