Newsletter Issue 33 (July 2023)

The Weather of June 2023 – A hot June

June 2023 was hotter than usual in Hong Kong due to the warmer than normal sea surface temperature over the northern part of the South China Sea and the prevalence of southerly flow. The monthly mean maximum temperature of 31.9 degrees and monthly mean temperature of 29.2 degrees were respectively 1.2 degrees and 0.9 degree above their normals, both ranking the fourth highest on record for June. With all six months warmer than usual, the first half of 2023 was abnormally warm.

Preliminary data shows hottest week on record. Unprecedented sea surface temperatures and Antarctic sea ice loss

The world just had the hottest week on record, according to preliminary data. It follows the hottest June on record, with unprecedented sea surface temperatures and record low Antarctic sea ice extent. “The exceptional warmth in June and at the start of July occurred at the onset of the development of El Niño, which is expected to further fuel the heat both on land and in the oceans and lead to more extreme temperatures and marine heatwaves.” said WMO Director of Climate Services.

Record North Atlantic warmth – Hottest June on record globally

During May 2023, sea surface temperatures globally were higher than any previous May, a trend that continued through June, with the global ocean seeing higher sea surface temperatures than any previous June on record:
– Global ocean saw higher sea surface temperatures than any previous June on record
– Exceptionally warm sea surface temperature anomalies were recorded in the north Atlantic, caused by a combination of short-term anomalous circulation in the atmosphere and longer-term changes in the ocean

Earth’s hottest day in modern history likely recorded July 4; same record tied again on July 5

It is very likely that the Earth’s global temperature reached a new modern-day record high, not just once, but on three consecutive days that broke or tied records. According to the National Oceanic and Atmospheric Administration, July 3, 4 and 5 all consecutively broke records as the Earth’s hottest day since scientists began recording in 1979.

WMO declares onset of El Niño conditions

El Niño conditions have developed in the tropical Pacific for the first time in seven years, setting the stage for a likely surge in global temperatures and disruptive weather and climate patterns. A new Update from the World Meteorological Organization (WMO) forecasts that there is a 90% probability of the El Niño event continuing during the second half of 2023. It is expected to be at least of moderate strength. The WMO Update combines forecasts and expert guidance from around the world.

NOAA index tracks how greenhouse gas pollution amplified global warming in 2022

Stratospheric ozone is slowly recovering, with a full recovery in most parts of the atmosphere projected to occur in the coming decades. The map, shows that in 2022, higher than normal ozone columns were observed in the tropics and subtropics and lower than normal ozone columns at higher latitudes, particularly in the southern hemisphere. The ozone layer protects life on Earth from harmful solar ultraviolet radiation, thus ozone observations are critical to protect human and environmental health. [WMO Ozone and UV Bulletin]


基於ERA5逐小時資料,中國科學院大氣物理研究所的 研究論文揭示了中國區域極端日夜複合濕熱和高溫事件的變化及其影響。高溫天氣易使環境溫度超過暴露人群的耐熱極限,這不僅會影響人們的正常生產生活,還會增加人體的發病率和死亡率。隨著全球變暖,濕度的增加使得某些高溫熱浪事件的強度在增強。如果在濕度較高的水準下體溫超過這個閾值(約為36.5℃,且在±1℃非常窄的範圍內波動),人體將無法通過蒸發有效散熱,從而加劇與高溫有關的熱不適。因此,對人體來說,高溫高濕的環境比僅高溫條件更具生理挑戰。

WMO launches 2024 Calendar Competition

The World Meteorological Organization is thrilled to announce the launch of its 2024 calendar photography competition. It is one of our most eagerly awaited annual activities. Each year becomes even more successful with an ever-increasing number of amazing photographs which illustrate the beauty, power and importance of weather, climate and water. This year, the competition will reflect the theme of World Meteorological Day 2024: At the frontline of climate action.

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The news in the Newsletter will be presented in the originating language only.