As of Wednesday morning, dense fog enshrouded the city of London.
The thick fog rolled into the region around midnight local time and lasted through mid-morning, creating heavy traffic delays during the morning commute.
For five hours, the city had zero visibility conditions, and for nearly eight hours, visibility was down to 1/8 mile.
By Wednesday afternoon, more than 800 arriving and departing flights were cancelled or delayed at London Heathrow Airport, according to FlightStats data.
While this time of year is favorable for fog across the Northern Hemisphere due to longer nights and more time for morning fog to form, weather conditions in the city late Tuesday evening were prime for fog formation.
"Clear skies and calm winds are the main causes of fog," said AccuWeather Meteorologist Dan DePodwin said. "Wind yesterday was out of the southeast so that helped bring moisture to the area."
Moisture, clear and calm skies are the perfect combination for this kind of all-encompassing fog.
London is not expected to have another fog incident again this week, but instead some stormy weather is in store for the city.
This aerial photo captured by the London Metropolitan Police helicopter crew, on Twitter as @MPSinthesky, shows everywhere but central London enshrouded in fog.
Fog surrounds the city of London. Photo courtesy of Twitter user @TheDJCull.
Canary Wharf is enclosed by fog with only the tops of buildings visible. Photo courtesy of the London Metropolitan Police helicopter crew.
This part of London is almost unrecognizable due to the heavy fog, photo attributed to the London Metropolitan Police helicopter crew.
The combination of moisture from Erika and a non-tropical system will drench areas from Florida to the Georgia coast through the middle of the week.
A rapid shutdown of tropical activity and an end to hurricane season in early September is not likely this year, despite a strong El Nino.
Typhoons and building drought will impact more than one billion people in southeastern Asia this fall.
The calendar may have flipped to September but summer is not going anywhere just yet across the Northeast.
Tropical Depression 14-E developed several hundred miles southwest of Mexico on Monday and is expected to strengthen as it moves northward through the middle of the week.
Heat will be erased by an autumnlike air mass across parts of northern Europe.
Yuma, AZ (1950)
123 degrees - hottest temperature ever in Yuma. Yuma is the hottest city in the U.S.
Los Angeles, CA (1955)
110 degrees, hottest day ever in September. This mark was tied September 4, 1988.
Milwaukee, WI (1988)
Hottest summer on record. Six days of 100 degrees or greater and 36 days of 90 or above. Average temperature of 73.8 beat the old record of 72.8 set in 1921 and 1955. The normal average tempera- ture for a summer in Milwaukee is 68.3 degrees.