Tropical systems often strengthen in warmer areas of Atlantic, but can also intensify elsewhere in certain conditions

Late last week, Canada’s Atlantic coast was hit by Hurricane Fiona, with maximum sustained winds in the region of 90mph (145km/h). Hurricanes rarely maintain such an intensity that far north. Why? Hurricanes are fuelled by high sea surface temperatures (SSTs), and ideally high sea temperatures over a large depth. As you move away from the tropics, SSTs typically reduce.

But hurricanes are not confined to the warmer areas of the Atlantic, such as the Gulf of Mexico and the Caribbean Sea. Tropical systems often strengthen in these regions, but can sometimes sustain or even strengthen elsewhere given favourable conditions. Ocean currents can transport warmer water poleward which can produce regions at higher latitudes that have higher SSTs than their surroundings. Tropical systems that track northwards over warmer seas can maintain intensity or even strengthen, such as happened with Hurricane Fiona.