Britain may face increasingly muggy weather conditions during September as rising sea temperatures contribute to more frequent marine heatwaves in the autumn months, according to meteorologists. This shift is linked to warmer and longer-lasting summer conditions that have raised ocean temperatures, particularly in the Atlantic, leading to higher humidity levels inland.

In recent days, humidity levels on the south coast of Britain have exceeded 90 percent, driven by warm, moist air masses arriving from the Atlantic. Alex Burkill, a meteorologist at the Met Office, explained that a persistent high-pressure system has been steering this warm, wet air over the region. He noted that while humid conditions are not unprecedented, current levels are unusually elevated for this time of year. The combination of high humidity and temperatures above average is making September weather feel particularly muggy.

This year, Britain recorded its hottest summer since national weather records began in 1884, surpassing the previous high set in 1976. The average daily maximum temperature over the summer reached 21.3 degrees Celsius, exceeding the 21.0 degrees recorded 50 years ago. The extended heatwave brought severe dry conditions, culminating in drought declarations across nearly 75 percent of England and Wales.

Marine heatwaves, periods of significantly elevated sea surface temperatures, have become more common due to the sustained heat and warm nights, which limit the sea’s ability to cool. The National Oceanography Centre reported that the southern English coast is currently experiencing a marine heatwave, with sea surface temperatures around 2 degrees Celsius above normal for September. Because ocean water cools more slowly than air, these heatwaves have the potential to extend into early autumn, even as daytime air temperatures begin to decline.

Burkill highlighted that warmer Atlantic waters influence the atmosphere by increasing evaporation, which in turn raises humidity levels over the region. This persistent pattern suggests that Britain’s early autumn weather may become more characteristic of a warmer, wetter climate in the future, with implications for daily life such as increased discomfort and frizzy hair caused by the muggy air.