Rising temperatures are reducing the frequency and intensity of cold spells in the Northern Hemisphere, scientists warned.

A new study by Weronika Osmólska at the National Centre for Atmospheric Science and University of Leeds researched the changes in cold spells between 1980-2025, using a new method that tracked cold spells in space and time.

For the research she analysed four cold spell characteristics – frequency, intensity, area, and persistence.

Though there can be other contributing factors to changes in cold spells – such as loss of sea ice and shifting weather patterns which can change how much temperature fluctuates about the background warming – Weronika’s research found that the dominant driver to decreasing cold spells is the rise in Earth’s average temperatures. Global warming is making cold spells less frequent, less intense, and smaller across most of the Northern Hemisphere.

Weronika explained: “Local cold events in this study were identified when the temperature dropped below the fifth percent of all temperature values for three consecutive days. Events that meet this requirement are then tracked. We use the winds over the event area to estimate where the cold extreme might be present on the next day. If there is an extreme in this region on the next day, we label this as part of the same cold spell event. This way we build a catalogue of all cold spells, with the knowledge of their location and pathway.”

“This is the first study that considers and compares how cold spells have changed as a result of mean background temperature rise and also from changes in the temperature variability about this background temperature rise,” she emphasised.

When asked about the most unexpected discovery during her research, Weronika said: “Only in Northern North America, the reduction in temperature variability about the background mean warming was found to also significantly decrease the frequency and the severity of cold spells. More specifically, we find that the changes in these temperature variabilities in northern North America are found to contribute to one third of the total change in intensity from mean background warming effects.

“Based on other studies this reduction of temperature variance might be caused by sea ice loss, leading to cold extremes warming faster than hotter extremes.”

Research published by the Intergovernmental Panel on Climate Change (IPCC) confirmed that winter cold spells have been decreasing since 1950 and that anthropogenic greenhouse gases are very likely the main cause for this.

Weronika continued: “In Europe, studies show there has been a decline in cold spell frequency, with a severity comparable to the European cold winter of 2009/10 being half as likely to occur as a consequence of anthropogenic climate change. IPCC reports also state that, on land, the magnitude of temperature extremes increases more strongly than global mean temperature, and the highest increase of temperature is projected in Arctic regions, at about three times the rate of global warming.”

Weronika concluded “This is a clear sign of how the next generations are already experiencing a different winter than we did because of global warming. A better understanding of how temperature extremes will change in the future will help us better prepare and adapt to our changing climate.”