Hurricane Douglas this afternoon near Hawaii
Hurricanes hitting Hawaii are unusual but not rare. Here is a map of hurricanes that came within 75 miles of the islands since 1950. Kauai has been the hurricane hotspot for the islands. One reason that hurricanes are fairly rare in Hawaii is because the water temperatures are often too cool.
The current forecast track takes the storm across Kauai tonight and to the west on Monday. So the action is going on now and during the next 18 hr.
Fortunately, this is a small system, and only a Category 1 storm, with winds reaching 85 mph. But tropical storm winds (greater than or equal to 39 mph) will hit Kauai and northern part of Oahu during the next day.
The maximum winds so far (below) have only gotten to roughly 35 mph at official observing stations, but higher speeds are expected.
The storm is forcing some large 8-9 meter waves, as predicted tonight by the NOAA/NWS wavewatch3 model:
The other issue is rain, and some locations will probably get 5-10 inches, with the potential for flash flooding. A recent infrared satellite image does not show a well-defined eye (see below)
But the eye is quite evident in the NOAA/NWS radars (see below). You can see the rainbands circling the rain-free eye. Kauai in particular will get a piece of the heavy rain in the encircling rainbands.
Finally, I should note that the U.S. global model–the GFS–did an excellent job with this storm. Here is the 66 hr forecast valid Monday at 5 AM PDT. Not bad. The kind of forecast that allows people to prepare.