Home / Weather News /

How does fog form?

10:00
19 May 2023

Weather explained
How does fog form?

fog-shutterstock

The sight of fog is not rare across the UK and Ireland, but do you know exactly what it is and why it appears?

There are actually five different types of fog that form in slightly unique ways. Cloud cover, wind speeds, temperature, moisture levels, and daylight hours all play a role.

Despite fog being somewhat regular during cooler months, it is harder to forecast than you might think.

This is because if just one of the many factors that are needed for development are slightly out of sync, the fog does not arrive. Meaning even small miscalculations in a forecast can miss or inaccurately predict a foggy day.

In addition to regular fog, we also see freezing fog in the UK and Ireland. This occurs when fog develops in below-freezing temperatures.

Freezing fog sees moisture supercooled in the air, when this moisture makes contact with a surface it instantly freezes and creates what is called rime.

This is a layer of tiny ice crystals, creating wintery landscapes.

Ryan Hathaway
More on the topic
Monday 30 June 2025

Noctilucent cloud season

Shimmering clouds over UK and Ireland
Monday 23 June 2025

Gusts of up to 45 mph

Wind warnings start the week
Friday 27 June 2025

Noctilucent clouds

Season of the shimmering clouds
All weather news
This might also interest you
Thursday 3 July 2025

Gusty too

Rainfall passes through the north
Wednesday 2 July 2025

Breakfast brief

Cooler with stormy potential
Friday 27 June 2025

Breakfast brief

Rain for some, heat returns elsewhere
All articles
Weather & Radar

www.weatherandradar.ie

facebooktwitteryouTubeContact uslinkList
Privacy Policy | Legal info | Accessibility statement