Parents will want to ensure their little ones have a few extra layers of clothing on under their Halloween costumes before they hit London streets trick-or-treating Wednesday evening.
While the daytime high Wednesday is forecast to be above normal at 14 C, Environment Canada expects the temperatures to drop to plus 4 C at night.
"It will be warm during early parts of the day, but unfortunately with the passage of a cold front it is going to dip in terms of temperatures towards the evening hours when everybody is trick-or-treating," said Environment Canada meteorologist Gerald Cheng. "So all of those ghosts and goblins better put something warm underneath their costumes."
The national weather agency also anticipates rain and thunderstorms will clear out long before the kids start going door-to-door for candy. The sun is expected to set around 6:20 p.m., added Cheng.
As for the start of November, it will be a wet one with rain in the forecast for the first five days of the month with the temperature hovering around the 9 C mark. The average temperature for the region this time of year is around 10 C.
"If we look even further ahead for November, we should stick to almost normal temperatures for the most part," said Cheng.
