Guillermo (2015)

A tropical depression formed about 1,200 miles southwest of the southern tip of the Baja California peninsula on July 29, 2015, from a tropical wave that had crossed the Atlantic. It strengthened to a tropical storm on July 30 and became a hurricane on July 31. Guillermo moved west-northwest across the eastern North Pacific into the Central Pacific basin, weakened to a tropical storm on August 3, and degenerated to a post-tropical low by August 7 as it neared the Hawaiian Islands. The system dissipated a few days later north of the islands.

Guillermo did not make any landfalls. It remained well offshore for its entire life, moving across open water from the eastern Pacific into the central North Pacific and passing to the north of the main Hawaiian Islands without producing tropical-storm-force winds onshore.

The hurricane’s maximum intensity was 95 knots (about 110 mph) at 1800 UTC on July 31, with a minimum central pressure of 967 mb. At peak intensity it was a Category 2 hurricane on the Saffir–Simpson scale.

Storm surge impacts in populated areas were not reported, and no significant coastal surge heights were recorded for the Hawaiian Islands. Rainfall associated with Guillermo was limited across the islands; the report does not list large rain totals at specific cities or counties tied to this system. No tropical-storm-force winds were observed on the islands.

There were no reports of damage or casualties—no direct or indirect deaths were attributed to Hurricane Guillermo. The areas closest to any effects were the Hawaiian Islands, where a tropical storm watch was issued for Maui County and the Island of Hawai‘i on August 4 but was discontinued on August 5 when the threat diminished.

Noteworthy items include that Guillermo was the second cyclone in 2015 to cross from the eastern Pacific into the central Pacific. The storm’s formation was not well anticipated far in advance, with high formation probabilities issued only shortly before genesis. NHC and the Central Pacific Hurricane Center generally produced track and intensity forecasts that compared favorably with model guidance; official intensity forecasts were better than most model guidance for this storm.