Smoke continues to flow over much of northern California this afternoon ahead of much hotter weather for this upcoming Labor Day weekend. That smoke prevented us from getting too hot today, but the heat could be potentially dangerous at times by Sunday and Monday, with an Extreme Heat Warning in effect from Saturday morning through Tuesday evening. Tonight will be a clear night with areas of haze and smoke. Lows will range from the 40s and 50s in the mountains to the 60s and 70s in the foothills and valley. Saturday will be a hotter day with a lot of hazy sunshine. Highs will be mainly in the 90s from the mountains to the valley, with only a few upper 80s possible, and more 100s in the hotter valley locations than today.
The strong ridge of high pressure over California and the western United States will only get stronger Sunday and Labor Day Monday as hotter and potentially dangerous weather continues. Not only will the daytime highs be well above average for September, but the overnight lows won't cool enough for real relief. A trough of low pressure will brush past northern California to the north on Tuesday, and slightly stronger wind is possible. That will also increase our fire danger, with a Fire Weather Watch in effect from Monday night through Wednesday morning. Sunday and Monday will be the hottest days, with a minor cooling trend through next week. Highs will stay in the 90s and 100s, with some lower 110 degree highs possible.