PLAY IT SAFE. FIRE DANGER, HEAT SOAR THIS WEEK.

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Even by California standards, the coming week to ten days of building heat and rising fire danger is significant. The peak of our heat will likely come on Tuesday, however the most current forecasts suggest there will be multiple peaks, with the thermometer staying well above October averages for at least a week, and likely closer to two weeks.

Although the NWS has issued heat advisories and excessive heat warnings for the region from Monday-Wednesday, more official advisories are likely in the coming days.

Although the greatest fire danger will come with wind events Monday and Tuesday, the good news is that those will be only mild to moderate by Northern California standards. The more troubling news is that the prolonged heat will wring most remaining moisture out of vegetation all across the region, leaving the so called Energy Release Component, or combustibility of fuels, near record levels. This, coupled with continued low humidity and poor nighttime humidity recoveries in the hills, will keep the fire danger very high.

This chart shows the current forecast of the ERC for the Bay Area north to around Mendocino. The blue line is current, the green line is the forecast, and the red line is the historical maximum. You can see that the (current) forecast calls for the ERC to peak around October 6th or 7th.

So this critical measure of fuel combustibility will be elevated and peak (at near record levels) days after the worst of the current heat wave passes.

A closer look shows the green line (forecast of ERC) peaking near October 6th.

That means the danger of fire starts will remain very high right into mid-October. Yes, we have become familiar with that kind of forecast in October, but still, this current heat wave remains very significant.

This loop shows how high pressure aloft will build over Northern California, and then only very gradually move east over the next week.

And this loop shows heat in the upper atmosphere reaching “off the charts” levels, again centered over Northern California, over the coming week. This atmospheric heat directly translates to heat waves where we live, at the surface.

Finally, to get a better idea of how the heat will linger for many days with multiple peaks, this graphic shows the first afternoon peak on Tuesday. Up to 25+ degrees above October averages for the North Bay! That means widespread high temperatures from 98-107.

But, while there will be slight cooling at times, the next 10 days will have other peaks. Check out this forecast of the temperature departure from averages for next Sunday. Again, more than 20 degrees above “average”, or once again highs in the 95-105 range (potentially higher along the central coast) for extensive regions of the California coastal plains, including the North Bay.

So, once again the takeaway is clear. Be safe with fire or anything that can create a spark. Stay indoors if possible during the afternoon heat. Hydrate. And be prepared for a very long and near record October heatwave this week, and expect anomalously high heat to hold on for the next 10 days or even 2 weeks.