Does dewpoint matter when the temp is below 25°C?

[Vivaldi]

Does dewpoint matter when the temp is below 25°C?

[SueShe]

Of course it does matter, regardless of the positive temperatures.

Everyone in aviation will tell you that if the dew point is too close to the actual temperature, fog will start forming and even the most performing airplanes, unless certified to land in ILS CAT 3C (zero/zero visibility) need a minimum of horizontal and vertical visibility.

If the runway is not visible when reaching the decision point, a go around has to be initiated by the pilot.

Thus, dew point is important in the aviation industry, even when the outside temperature is below the 25° Celsius and that for safety reasons.

[Vivaldi]

Nope fog does not start when dewpoint is close to temp

It was 21.7°C with 97% humidity and the sky was perfectly clear.

[Vivaldi]

It was in the morning