ALT JPEG version of a 1-page Factsheet: El Niño 2026-2027: A Potentially Historic Global Climate Event By Daniel Swain, PhD | August 2026 There is a banner image depicting projected warming of the Pacific Ocean by early winter. The content begins: "What is El Niño? El Niño is the warm phase of a natural cycle, known as El Niño/Southern Oscillation (ENSO), that occurs roughly every 2-7 years in the tropical Pacific Ocean. During El Niño events, the eastern tropical Pacific Ocean warms to well above typical levels. El Niño directly affects local climate in the countries closest to the unusually warm ocean waters, but can also indirectly influence the climate of distant regions thousands of miles away. During the strongest events, El Niño can profoundly affect climate even on global scales, causing temporary planetary warming and disrupting large-scale precipitation patterns..."

ALT Key Messages: 1. Tropical Storm Nolo is expected to strengthen into a hurricane on Thursday as it moves northward, potentially making its closest approach to the Big Island of Hawaii on Saturday. A Hurricane Watch is now in effect for the Big Island, and residents there should follow advice given by local officials, including evacuating if told to do so. 2. The time to prepare for significant heavy rain and flooding impacts on the Big Island is now, as heavy rain becomes more likely by Thursday and Friday. Periods of heavy rain are likely to continue across the Big Island and Maui through the weekend. Life-threatening, catastrophic flooding and mudslides are possible, especially in areas of steep terrain across the Big Island and Maui. Across the remainder of Hawaii, lesser rainfall totals are expected, with isolated flooding possible. 3. Large and damaging waves are possible along the coast of the Big Island into the weekend.