Dry and mild month for Wick as temperatures rise
Weather Watch by Keith Banks
Noctilucent cloud events are relatively rare meteorological phenomena that occur only close to the ceiling of the third and coldest layer of the Earth’s atmosphere, the Mesosphere, where temperatures are below minus 120C (-184.0F).
They are visible from the Earth’s surface at higher latitudes and altitudes in the range of between about 40 miles to 60 miles above the planet’s surface.
Noctilucent clouds are only visible during the summer months in both hemispheres for several hours after sunset at latitudes between about 50 degrees N/S and 70 degrees N/S respectively.
The optimal period to see NLCs in Caithness, together with other parts of the far north of Scotland, is a relatively narrow window of time from mid-June until mid-July on cloudless nights. Noctilucent events manifest in the direction of the poles. The majority of observations are in the the northern hemisphere.
These noctilucent (NLCs) or “night shining clouds”, also known as polar mesospheric clouds (PMCs), superficially resemble the cirrus clouds that are located in the troposphere.
NLCs tend to have an undulating structure, look fibrous, long drawn out, look silver-white, often with a pale bluish tone. They are so thin and delicate that the stars shine through them.
Noctilucent clouds are known to be composed of water-ice crystals that are believed to have become deposited around tiny particles of meteoric dust, (sometimes called meteoric smoke), that is present in the mesosphere.
These minute fragments are the remnants of meteors that have entered the Earth’s atmosphere that meteorologists refer to as “freezing nuclei”. However, the actual mechanisms and specifics of the physical processes that create these rare clouds are complex and not fully understood, and are currently the topic of research.
April 2025 was Wick’s mildest since that of 2011, and is currently the third most mild in a series of Aprils stretching back to 1910.
In terms of precipitation, April 2025 was Wick’s driest since that of 1966. A closer look at the town’s rainfall archive for a series of Aprils commencing from 1910 confirmed that is presently the third most dry.
Wick’s mean air temperature for April 2025 was 8.64C (47.55F). The long-term average in terms of the averaging period 1991-2020 is 6.94C (44.49).
Wick’s average daily maximum air temperature for April 2025 was 11.89C (53.40F). The long-term average for this variable, in terms of the current 30-year averaging period, is 9.97C (49.95F).
Highest daily maximum was 18.3C (64.9F) recorded on April 30.
Lowest daily maximum was 8.3C (46.9F), witnessed on April 5.
The burgh’s average daily minimum air temperature for April 2025 was 5.38C (41.68F), 1.48C higher than the current long-term average for the month.
Highest daily minimum air temperature was 11.7C (53.1F), noted on April 28.
Air frosts occurred on three days.
The lowest daily minimum air temperature for the month was minus 0.7C (30.7F), recorded on April 8.
The temperature fell to 0.0C (32.0F), or lower at 5cm over the grass on seven dates. Lowest temperature over the grass was minus 3.2C (26.2F), observed on April 8.
Precipitation was measurable on 16 dates. The total amount recorded for the month was 13.4mm (0.53 of an inch), or 28.2 per cent of the average quantity for the month.
Wettest day was April 16. The total amount recorded for the 24-hour period commencing 9am (GMT) was 5.4mm (0.21 of an inch).
There were no “days of gale”.
The windiest day was April 27, when a force 4 southerly wind gusted up to 33.3mph/28.9knots, force 7 on the Beaufort scale, during the hour ending 5am (GMT).
An aurora borealis event occurred on April 3.