In a world where climate change makes every season unpredictable, we have perhaps got used to unseasonal warm spells. But if I cast my mind back to the middle of February 1998, I can still recall my surprise at the unusually mild weather.

I was filming at a west London gravel pit with Bill Oddie, and during the course of the day we saw four different species of butterfly on the wing. They were the quartet that habitually overwinter as adults – comma, peacock, small tortoiseshell and brimstone – each emerging on a mild spring day to feed on nectar.

The cause of this unexpected warm spell was high pressure over the continent, which brought warm air up from the Canary Islands and north-west Africa. This tropical maritime airstream meant temperatures reached the mid-teens across much of southern Britain, and even at night stayed much higher than normal. On 13 February, at Greenwich in south-east London, the temperature reached 19.7C (67.5F), breaking the UK February record.

Of course, it could not last, and by the 15th a cold front began to bring slightly cooler air – along with Sahara dust. But for a few days, we had a preview of what winters might be like if we cannot stop climate change – and, butterflies aside, it was disturbing.