July weather blog: Why time is moving faster and when to see the Delta Aquariid meteor shower

ITV News

10-07-2025

We are now well into the summer and have already experienced temperatures rising into the high 20s.
But what can we expect for the rest of this month?
Read on for the answer to all of your meteorological musings.
July weather
July tends to be one of our driest months of the year, with the average rainfall of 45mm only measuring a third of what is expected across December.
This could be interpreted as roughly 1.5mm per day, but in July it is more typical for the rainfall to come in just a handful of sporadic showers, whilst most days stay dry.
July is also a sunny month, according to climate records, featuring approximately 8.8 hours of sunshine a day - on par with June, despite having marginally fewer daylight hours.
Dry and sunny weather tends to occur when an area of high pressure sits over us, usually extending from the Azores or mainland Europe.
As well as being dry, July is often one of our hottest months of the year - with the same average daily maximum temperature as August, which is 22°C in Jersey and 19.6°C in Guernsey.
As we progress through the summer, the ground stores up heat - the power of the sun is strong and with shorter nights than days, there is more time for the earth to warm than there is for it to cool.
This warm surface temperature can combine with warm air temperatures on a sunny day to give us hotter weather.
As we progress through the summer, the ground and surrounding sea store up more and more heat – even though, after the solstice in June, the power of the sun actually starts to slightly wane and the days slightly shorten.
The warmer sea and earth significantly limit overnight cooling, which means that we generally start each day at a higher temperature than in June and can easily climb to higher maximum temperatures, despite the reduced intensity and duration of sunlight.
However, it must be noted that July's sunshine is still very intense compared to the rest of the year, with the UV index typically reaching 8 in the first half of the month and 7 in the second.
Well technically, time is moving a bit faster.
Usually, there are 24 hours in a day or 86,400 seconds.
But it can vary by a few milliseconds, depending on how quickly the Earth rotates.
Listen to Richard Holme, a professor in geophysics, explain what is causing shorter days and whether this trend is set to continue
This variation is due to a complicated interplay of atmospheric changes, movement of the Earth's core, and the moon's effect on the tide.
Even simple things like the wind blowing on the rocky mountains can affect the speed of the Earth's rotation.
Since 2020, scientists have noticed the Earth moving faster and several factors are combining across three dates in summer to give us our shortest days on record.
Pluto's perigee and July's night skies
The full moon peaks on the 10th of this month. It is known as a 'buck' moon, so-named as it coincides with the time of year when male deer (bucks) start to grow new antlers.
Soon after, we are treated to a meteor shower, with the Delta Aquariid shower starting on 12 July. It peaks later in the month, around 28 and 29 July, when we could see from 15 to 20 meteors an hour.
The best time to see the meteors is in a dark place, away from artificial light, after midnight.
Pluto is set to shine brightly as it reaches a perigee on 25 July - this is the point in its orbit when it is closest to the Earth.
While it is one of your best chances to spot the dwarf planet this year, a telescope is still handy as it could still be quite hard to see without equipment.
July wildlife watch
During the summer months, it is not uncommon to spot pods of dolphins along our coastlines.
They are inquisitive creatures, so you may have a better chance of seeing them if you can get on the water in a boat or kayak.
July brings the first of the autumn bird migrants south. Keep an eye out for small gulls, Mediterranean gulls and the black-headed gull.
July is also good month to spot puffins, as they will be busy feeding their chicks. Remember it is important to avoid getting too close and not to disturb the birds during breeding season.
In terms of our flora, white sea campion can be found coating our coastal cliffs.
Banks and hedgerows can be full of small blue sheep's-bit and honeysuckle at this time of year, while galingale flower and bog pimpernel may be spotted in damp meadows.
The Eiffel Tower in Paris grows taller on a hot day - this is because it is made of iron which expands in warm weather. It can grow by up to 17cm.
July Fact File
Average daily maximum temperature:
22.0°C
in Jersey
19.6°C
in Guernsey
Average daily sunshine hours:
8.8
in Jersey
8.2
in Guernsey
Average daily rainfall total:
1.46mm
in Jersey
1.39mm
in Guernsey
Dates for the diary
9 July, 22 July (+ 5 August) - scientists predict some of our shortest days on record
10 July - Full 'buck' moon
12 July - Sark to Jersey rowing race
12 July - Delta Aquariid meteor shower begins
18 and 19 July - Sark sheep racing
25 July - Pluto reaches 'perigee'
28 July - Delta Aquariid meteor shower peaks
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