SAN DIEGO -- Santa Ana winds are expected to buffet San Diego County early next week and combine with dry conditions to increase the threat of late-season wildfires.
"There will be potential for a moderate to strong Santa Ana event beginning Tuesday next week and possibly continuing through the work week," National Weather Service forecaster James Brotherton said. "There will be the potential for widespread critical fire weather conditions due to a combination of low relative humidity, strong northeast to east winds and dry fuels."
The U.S. Forest Service predicted the Santa Ana winds will begin earlier, on Monday, and continue at least until Wednesday, with the strongest winds and lowest humidity levels expected Tuesday.
According to the Forest Service's Santa Ana Wildfire Threat Index, winds will be 15 to 30 mph on Monday with 10 to 15 percent humidity. On Tuesday, winds are forecast to increase to 20 to 35 mph with 7 to 15 percent humidity. Wednesday's conditions are forecast to be nearly identical to Tuesday's but with maximum winds hitting 30 mph. The Forest Service does not yet have forecasts available after Wednesday.
According to the threat index, which ranks Santa Ana-driven wildfire threats as extreme, high, moderate, marginal or no rating, the wildfire danger will be marginal on Monday and moderate both Tuesday and Wednesday. The marginal rating means that "upon ignition, fires may grow rapidly." The moderate rating means that "upon ignition, fires will grow rapidly and will be difficult to control."
San Diego County's mountains and valleys are the areas expected to be affected by the strong winds and critical fire weather conditions, Brotherton said. But the impact area will "possibly (be) all the way to the ... San Diego county coasts."
The factor that could help mitigate the danger will be the relatively mild temperatures in the forecast next week. Monday calls for highs of 71 to 76 near the coast, inland and western valleys, 62 to 67 near the foothills and 50 to 60 in the mountains.
Tuesday's forecast calls for highs of 69 to 74 near the beach, inland and western valleys, 58 to 63 near the foothills and 46 to 55 in the mountains. Wednesday calls for highs of 69 to 74 at the beaches, 73 to 78 inland, 74 to 79 in the western valleys, 68 to 73 near the foothills and 55 to 65 in the mountains.