For tourists on Oahu, even a weakening Tropical Storm Olivia could force plans to change, especially if those plans involved the ocean.

The storm will likely kick up waves and bring heavy rain, meaning swimming could be dangerous. Officials warned tourists Tuesday to stay out of high surf and brown water.

The popular snorkeling spot Hanauma Bay will be closed today due to anticipated high surf.

Honolulu Mayor Kirk Caldwell cautioned residents and tourists not to put themselves or first responders at risk.

“We’re asking folks before they go into the water to listen to our Ocean Safety officers,” Caldwell said during a Tuesday afternoon briefing with city and state officials, including Gov. David Ige.

Jim Howe, Honolulu Emergency Services director, said the storm is expected to bring a lot of ocean safety impacts, including beach erosion, high surf and brown water, which increase recreational risks. Tourists should be especially cautious since they may not be as adept at managing local water conditions as residents, who make it look “awfully easy,” Howe said.

“The runoff flushing debris does draw our sharks into nearshore waters to feed,” Howe said. “If it’s brown, don’t go into the water. It’s not just something that could make you sick. Animals could be there.”

Howe also warned beachgoers to avoid eroded areas, especially on the North Shore, where beach access is limited and sand cliffs could collapse into the beach.

Howe said the city will keep lifeguards at Waikiki Beach until conditions become too dangerous. Honolulu Fire Department Chief Manuel Neves also warned tourists and residents to “choose outdoor activities wisely” because responders “may or may not be able to help you in the event of a true emergency.”

George D. Szigeti, Hawaii Tourism Authority president and chief executive officer, said the agency is strongly advising residents and visitors to heed the instructions of Hawaii’s civil defense officials and to stay informed.

“Stay safe, stay indoors and don’t do anything risky until Olivia has safely passed the islands,” Szigeti said in a statement. “The National Weather Service is providing accurate, timely updates that government officials and media are closely monitoring, but we know from experience that storm conditions can change rapidly and have greater impacts than predicted.”

HTA advises visitors to stay informed about Olivia and to contact their airlines, accommodations and activity providers to see whether adjustments to travel plans are needed. Hawaiian Airlines has canceled today’s ‘Ohana by Hawaiian flights to and from Maui County.

HTA is posting Tropical Storm Olivia updates at www.hawaiitourismauthority.org/news/alerts. The agency also distributed an electronic release Tuesday afternoon cautioning that all Hawaiian Islands were now under a tropical storm warning, meaning sustained winds within the range of 39 to 73 miles per hour were expected. HTA said all islands also are under a flash flood watch through Thursday.

Other than Hanauma Bay, all Oahu parks will remain open, Caldwell said. The Honolulu Zoo and all city golf courses will also remain open. Ala Moana Center, the International Market Place and the Royal Hawaiian Center also are expected to stay open through the storm.

The big event for Waikiki this weekend — Sunset on the Beach celebrating the 50th anniversary of “Hawaii Five-0” and the premiere of “Magnum P.I.” — was postponed to Sunday. It had been scheduled for Friday night. The event will feature cast members from both shows and a musical performance by singer Cyndi Lauper, who appears this season in an episode of “Magnum P.I.”

“Olivia will be long gone by Sunday,” Caldwell said.

WHAT’S OPEN AND CLOSED

Airports

>> State airports will remain open unless there is damage to the runway or terminal. Air travelers with confirmed tickets are encouraged to check with their airline for potential flight delays, cancellations or travel waivers.

>> Today’s ‘Ohana by Hawaiian flights have been canceled.

Banks

>> All First Hawaiian Bank Maui and Lanai branches will be closed today.

>> All Central Pacific Bank branches on Maui will be closed today.

>> Territorial branches in Lahaina, Kahului and Kihei, Maui, will be closed today.

>> Hawaii State Federal Credit Union’s Kahului branch will be closed today.

>> As of Tuesday evening, Bank of Hawaii said all branches would remain open.

Bus and refuse service

>> TheBus and TheHandiVan service on Oahu will run on its regular schedule, as will curbside trash pickup.

> Maui Bus will be canceled today. No trash pickup, and all landfills are closed on Maui County today.

County offices

>> All nonessential Maui County offices will be closed today.

> City and County of Honolulu employees are to report to work as usual.

Courts

>> Courts and court facilities in Maui County are closed today.

Events

>> CBS’ annual Sunset on the Beach event scheduled for Friday featuring the premiere of the “Magnum P.I.” remake and ninth season of “Hawaii Five-0” in Waikiki has been moved to 4:30 p.m. Sunday.

Harbors

>> All state small boat harbors, operated by the DLNR Division of Boating and Ocean Recreation, will remain open during the storm and provide safe harbor for small vessels.

>> The U.S. Coast Guard set port condition Zulu for commercial ports statewide. At Zulu, winds above 39 miles per hour are expected to reach the area within 12 hours. While port condition ZULU remains in effect, port facilities will be closed to inbound and outbound traffic until the storm has passed and crews complete damage assessment surveys.

Medical

>> All Kaiser facilities on Maui will be closed today. All other Hawaii island, Oahu and Kauai facilities will remain open.

>> The Veterans Administration Pacific Islands Health Care system will close clinics in Hilo, Kona, Maui, Molokai and Lanai today.

>> The Spark Matsunaga Ambulatory Care Clinic and Leeward Community Based Outpatient Clinic are closed today.

Libraries

>> Public libraries on Maui, Molokai and Lanai are closed today.

Parks

>> Hanauma Bay Nature Preserve will be closed today.

>> The Haleakala National Park summit and Kipahulu District closed at 2 p.m. Tuesday. No sunrise viewing today or tomorrow.

>> Maui County parks and park facilities are closed today.

Post offices

>> All post offices on Molokai and Lanai are closed today.

Schools

>> All public schools in Maui County will be closed today.

>> University of Hawaii Maui College and educational centers in Lahaina, Hana, Lanai and Molokai will be closed today.

>> Island Pacific Academy and St. Andrew’s Schools will close today.

Shopping

>> The Aloha Stadium Swap Meet is closed today, reopening Saturday.

>> The International Market Place and Royal Hawaiian Center intend to remain open and keep regular hours from 10 a.m. to 10 p.m.