Students in rural East County got a day off from school because of windy conditions while nearly 700 residents saw their power shut off as a safety measure because of heightened fire risks, officials said Wednesday. County officials announced Tuesday night that schools in the Mountain Empire Unified School District would be closed because of high winds. Windy conditions make travel on mountain roads difficult, especially for high-profile vehicles like school buses, the office said in a statement posted on X, formerly known as Twitter. The National Weather Services has issued a wind advisory and red flag warning for San Diego County through Friday morning. Forecasters are predicting strong gusty winds and low relative humidity in the valleys and coastal slopes of the county’s mountains — conditions that bring an elevated fire danger. “A red flag warning means that critical fire weather conditions are either occurring now or will shortly,” the National Weather Service said. Strong winds combined with low relative humidity and warm temperatures “can contribute to extreme fire behavior,” the agency said. Forecasters said to expect northeast winds of 20 to 30 mph with gusts up to 50 to 60 mph. San Diego Gas & Electric said it shut down power to 683 customers in the Campo and Boulevard communities as a public safety power shutoff. The wind advisory warns that tree limbs could be blown down, resulting in possible power outages, and urges drivers to use “extreme caution,” especially those driving high-profile vehicles.