It has among the most diverse climates of United States counties, with very mild coastal summers and hot interior days.

Its primary population centers of Eureka, the site of College of the Redwoods main campus, and the smaller college town of Arcata, site of California State Polytechnic University, Humboldt, are located adjacent to Humboldt Bay, California's second largest natural bay.

[14] Spanish traders made unintended visits to California with the Manila Galleons on their return trips from the Philippines beginning in 1565.

[14] The first recorded entry of Humboldt Bay by non-natives was an 1806 visit from a sea otter hunting party from Sitka employed by the Russian American Company.

It was the site of the February 26, 1860, massacre of the Wiyot people that was recorded by Bret Harte, then living in Union, now called Arcata.

State historic landmarks in Humboldt County include Arcata and Mad River Railroad, California's First Drilled Oil Wells in Petrolia, Camp Curtis, Centerville Beach Cross, the city of Eureka, the Victorian town of Ferndale, Fort Humboldt, Humboldt Harbor Historical District, the Jacoby Building, The Old Arrow Tree, Old Indian Village of Tsurai, the Town of Trinidad, and Trinidad Head.

[22] In 2010, a 6.5 magnitude earthquake struck offshore, 33 mi (53 km) west of Eureka, resulting in only minor injuries and some structural damage to houses and utilities, and no fatalities reported.

[23] In 2022, a 6.4 magnitude earthquake centered approximately 10 miles (16 km) from Ferndale caused damage, especially in Rio Dell.

[25] The coastal zone of the county experiences very wet, cool winters and dry, mild foggy summers.

The coastal zone experiences a number of frosty nights in winter and early spring, though snowfall and hard freezes are rare.

Occasional summer highs of 100 °F (38 °C) are common in eastern and southern parts of the county including Orleans, Hoopa, Willow Creek, Garberville, Honeydew, and inland river valleys.

The Humboldt Creamery, a significant producer of high-grade ice cream and other dairy products, operates from the original headquarters located at Fernbridge adjacent to the Eel River.

[46] As part of the Emerald Triangle, Humboldt County is known for its cultivation of cannabis, estimated to be worth billions of dollars.

[48][49] Proposition 215 allows patients and caregivers who are given a doctor's recommendation to legally (State level only) grow up to 99 plants in Humboldt County.

[50][51] However, in the years before Prop 215 (early 1970s – late 1980s), Humboldt County saw a large migration of the Bay Area counter-culture to the region.

[52] A Redway radio station, KMUD, in the past has issued warnings and alerts to the region with information on whereabouts of law enforcement on their way to raid marijuana gardens.

While the influence of CAMP in Humboldt County has waned with decriminalization of marijuana, there is a renewed interest at the state level regarding valid growing permits and environmental concerns.

[54] Yearly CAMP reports, published by the California Department of Justice, Bureau of Narcotic Enforcement (BNE) are available online through Cal Poly Humboldt's Special Collections.

Starting in 1983, the annual reports detail the organizational structure and names of individual participants, a summary of the season's activities, tactics, and mention of special successes, trends and hazards.

[54] County officials and the industry have encountered challenges in the transition from an illegal, underground economy to legal recreational cannabis sales that began in California in 2018.

They scan all ballots and release a file of the images with a digital signature, so candidates and the public can recount to find if the official totals are correct.

[97] Other local publications include The Independent,[98][99] the North Coast Journal,[100] the Ferndale Enterprise,[101] the Two Rivers Tribune,[102] the Isis Scrolls,[103] and The Lumberjack.

Since 2017, CBS affiliate KVIQ has been a low-powered station operated as part of a duopoly with KIEM, sharing the same studios.

[128] Cable TV channels are carried by Suddenlink Communications[129] and local programs are provided online through the Community Media Archive.

[130] The Digital Redwoods initiative of Access Humboldt is developing local networks to meet comprehensive community needs, including public, education and government purposes.

[183] Much of The WB's Hyperion Bay and the CBS show Blue Skies as well as an episode of Moonlighting were filmed in Humboldt County.

Humboldt County has also been the subject of multiple documentary miniseries including Discovery Channel's Pot Cops and Netflix's Murder Mountain.

Humboldt County has also been featured in episodes of On the Case with Paula Zahn, The Profit, Hamilton's Pharmacopeia, Top Gear, The Tonight Show with Jay Leno, Survivorman, Diners, Drive-ins and Dives, Finding Bigfoot, Treehouse Masters, Rescue 911, Walking With Dinosaurs, Somebody's Gotta Do It, Monsters Resurrected, Weediquette, Dan Rather Reports, Monster Fish, Beachfront Bargain Hunt, and many more.

[185] Humboldt County has also been the filming location for countless national television advertisements, including many major car commercials.

This 'secluded town' could very well be a reference to the unincorporated Briceland of Humboldt County, making The Enchanted Hunters in 'Humboldt Land', continuing the novel's grotesque fairy-tale veneer.