A low pressure system is expected to move into San Diego County early Monday, producing sharply cooler weather and possibly light, sporadic rain, especially across inland valleys and the mountains, the National Weather Service said. It’s also likely that the system will generate winds gusting upwards of 50 mph on Monday afternoon and evening along eastern Interstate 8, near the border of San Diego and Imperial counties. The winds can lead to perilous driving conditions. The system will broadly affect Southern California, aiding the firefighters battling blazes in Orange, Riverside and Los Angeles counties. San Diego’s daytime high Monday will be 70, which is 7 degrees below the seasonal average. The cooling will be partly influenced by the marine layer, which could be up to 6,000 feet deep or roughly 3 times deeper than it typically gets this time of year. Forecasters said the moisture will be higher inland, notably in places like Alpine and Ramona, and across Mount Laguna and possibly Palomar Mountain. The vegetation in those areas is far drier than normal, elevating the risk of wildfire. San Diego International Airport has recorded 12.41 inches of rain during the water year, which extends from October 1 to September 30. That’s 2.70 inches above normal. Monday’s coastal moisture isn’t expected to be significant.