California residents are bracing for a fall heat wave with temperatures of up to 90F this week that could spark more blazes to add to the 8,400 wildfires that have already burned more than 4 million acres across the state this year. Fire weather watches will go into effect in much of Northern California early Wednesday due to high pressure producing hot and dry conditions with gusty offshore winds, the National Weather Service (NWS) said. Peak gusts are likely to start late Wednesday, according to the NWS. Forecasts show temperatures up to 90F on Thursday. Temperatures on Wednesday and Friday are predicted to hit the high 80s.'#RegFlagWarning in effect for portions of Northern California for Wednesday through Friday for gusty winds and low humidity. This is #CriticalFireWeather so use caution outdoors,' Cal Fire tweeted on Tuesday.Scroll down for video Pacific Gas & Electric (PG&E) said it is likely that some circuits will be turned off to try to prevent fires from being started by damaged power lines..More than 8,400 wildfires have burned well over 4 million acres in California since the start of the year, but mostly since mid-August.. Share this article Share Most of the huge fires have been fully or substantially contained over the past eight weeks but thousands of firefighters remain on the lines.Earlier this week, Cal Fire investigators announced that they are looking at a possibility utility issue stemming from PG&E in the Zogg Fire, which killed four people and destroyed over 200 homes since sparking on September 27.PG&E equipment failures caused a number of significant fires in 2017 and 2018, which killed over 100 people and destroyed at least 27,000 properties.The utility company was forced to file for bankruptcy in the aftermath of those fires, which PG&E only recently emerged from.Investigators also said that the Bobcat Fire remains under investigation, with damaged power equipment now being viewed as a potential cause of the wildfire.The Bobcat Fire has been raging in California since September 6, when an undisclosed incident sparked yet another wildfire in the state. On Monday, Southern California Edison (SCE) sent a letter to the California Public Utilities Commission, detailing progress in the investigation into the Bobcat Fire.In the letter, SCE stated that US Forest Service (USFS) investigators took possession of a 23-foot line of conductor owned by SCE, according to Fox News.While the fire could've been caused by damage to the electrical equipment, lingering smoke at the time of the spark is also creating questions about vegetation being a root cause of the Bobcat Fire.SCE reportedly experienced a 'relay operation' at 12.21pm on September