🔥 Trending Hong Kong Issues Strong Monsoon Signal: What You Need to Know

The Strong Monsoon Signal (SMS) is a weather warning issued by the Hong Kong Observatory (HKO) when winds associated with either the summer or winter monsoon are blowing in excess of, or are expected to exceed, 40 kilometers per hour (km/h) near sea level anywhere in Hong Kong ¹²³. This signal is a crucial part of Hong Kong's weather warning system, alerting the public to potentially strong winds.

Purpose and Issuance Criteria

The primary purpose of the Strong Monsoon Signal is to inform the public and various sectors about the presence of significant monsoonal winds that could affect daily activities and safety.

• Wind Speed Threshold: The key criterion for issuing the SMS is a mean wind speed exceeding 40 km/h at sea level ¹².
• Monsoon Types: The signal can be triggered by both the summer and winter monsoons ¹².
• Winter Monsoon: Typically blows from the north or east ¹⁸.
• Summer Monsoon: Generally blows from the south or southwest ¹².
• Geographical Scope: The warning applies if these wind conditions are met anywhere within Hong Kong's territory ¹³.

Significance and Public Awareness

The Strong Monsoon Signal is an important warning, often colloquially referred to as "Black Ball" ³. While it indicates strong winds, it is distinct from typhoon signals, which are issued for tropical cyclones ⁴. However, there can be instances where the HKO considers replacing a Standby Signal No. 1 (a lower-level typhoon signal) with the Strong Monsoon Signal if monsoonal winds become the predominant threat ⁵.

Recent Occurrences

The Hong Kong Observatory frequently issues the Strong Monsoon Signal when conditions warrant. For example:

• On March 16, 2025, the Strong Monsoon Signal was issued at 8:50 A.M., with winds exceeding 40 km/h expected ⁶.
• More recently, on July 14, 2026, a Strong Monsoon Signal Special Announcement was issued, indicating that strong winds with a mean speed exceeding 40 km/h were expected ⁷.

These examples highlight the regular occurrence of this signal, particularly during the monsoon seasons, to ensure public safety and preparedness.