Circulation analogues cannot identify changes in rainfall extremes

Increases in extreme rainfall are often assessed using analogues methods to investigate changes in events with similar circulation patterns, however other complex processes also play a role. Great care needs to be taken in communicating findings, ensuring the research question is clearly defined and suited to the method, to avoid overstating confidence.

Many attribution methods are used to investigate extreme weather and climate events, enabling assessment of many different characteristics of such events. Different methods are suitable for answering different questions. For example, probabilistic methods can assess changes in frequency or intensity (Philip et al 2020). Storyline approaches can assess how an event would differ in a warmer (future) or colder (past) climate (Shepherd et al 2018). Circulation analogues—events with similar large-scale atmospheric dynamics to an event of interest—can be sometimes used to investigate the hazard as well as circulation patterns associated with extreme weather events.

Recently, circulation analogues have been used within rapid assessments of extreme weather events, providing statements about how similar events have changed through time published days to weeks after the event occurrence (e.g. Faranda et al 2024, Clarke et al 2025). Using reanalysis data, analogues are identified from two time periods—a past period with less influence of climate change and a present period with a stronger climate change signal. The difference between the two analogue sets is often used to make statements about whether similar events are hotter or wetter in the present period compared to the past. For example, one conclusion could be that similar events in the recent climate are 2 °C hotter than 50 years ago—answering the question: ‘how much hotter is a similar event in the present climate?’.