Winds have whipped the still growing Jerusalem Fire since yesterday, spreading it across the county line so it's now burning in both Lake and Napa Counties. It also grew from 14,000 acres late Tuesday to 16,500 acres this morning, or 26 square miles. It is only 6 percent contained, and 50 structures remain threatened.

The fire began Sunday just to the south of the still burning Rocky Fire (69,636 acres, 88 percent contained, 43 homes burned), and quickly expanded in size. As CalFire spokesman Captain Tony McHale said Monday, the conditions surrounding the Jerusalem and Rocky Fires are "Unprecedented. I haven't seen fuel moistures this low in my career."

As KTVU reports, at least 150 people have had to evacuate so far, many of whom had just returned to their homes after evacuating for the Rocky Fire. The two fires have now officially merged.

Over 1600 fire personnel are fighting the blaze, which so far has been difficult. Per CalFire, "The fire is burning in heavy vegetation and the lack of improved roads continue to hamper fire suppression efforts... Erratic winds are contributing to the increased fire activity and promoting high intensity uphill runs with short range spotting."

The cause of the fire is still unknown, but it first broke out along Jerusalem Grade Road on Sunday after 3 p.m.

Across the state there are now 16 active wildfires being fought by 11,000 firefighters.