Hi All,

After another sizzling week down south with temperatures again topping 30°C at the end of the week, this summer is turning out to be a really hot one for central and southern England at least. On the back of a dry spring you can only wonder how long it is before we hear the familiar sounds of water restrictions for our amenity sector. No such problem for the north of England and Scotland though where the issue has been totally the opposite with high rainfall and very little in the way of summer heat so far.

The weather has certainly been unpredictable from a forecasting perspective with higher actual temperatures than forecast in a 5-day format, hit and miss rain and a rapidly changing picture on the 10-day forecast to the extent where it has been almost totally unreliable from one week to the next :(. Wind levels have also been unpredictable (eh Frank) ramping up in the afternoon after a quiet morning.

Last week, like many, I watched storms pop up out of nowhere on the rain radar, deliver their deluges and then disappear as quickly as they started. We had nothing here but just down the road in Oakham, they had torrential rain, thunder and lightning and hail the size (and bizarrely) the shape of 2 pound coins. If you watch the footage on You Tube it looks like something out of a clip from the U.S during a Hurricane such was the force of the storm.

So is it another week of heat or do we have some rain on the way ?

General Weather Situation

Well definitely the latter because we have a trough system in place into which a low pressure system will slip down this week and bring rain a good way south over the U.K along with cooler night and day temperatures. That rain is already in place as I type this on Monday morning with a band stretching from North Wales across northern England up to The North East. We will see more in the way of showers forming in The South West, across South Wales and these will work their way across into Central England and The Midlands later in the day. Ireland and Scotland will also see showers but these will be more few and far between than across England. Light winds today and temperatures a good bit lower than yesterday with high teens under the rain and low twenties out of it.

Moving onto Tuesday and that low pressure moves closer to the south of England bringing with it a mass of rain that pushes into the south west of Ireland early doors and then across The Irish Sea into Wales and the rest of the U.K during the afternoon. There also looks to be some rain for Central Scotland during the day. The worst of the rain will be across the south of the respective countries, drawing a line from Galway Bay to Dublin and from The Mersey to The Humber. South of this you can expect a pretty wet Tuesday for sure. Being a low pressure system in a trough, it’ll be slow-moving and if anything it’ll intensify during Tuesday night to bring some heavier rainfall for some areas. A much cooler day for the south with mid-teens under that rain likely whereas Scotland and Ireland north of that rain band will be mid to high teens. Winds will be light again and that’s why the rain fronts are likely to be so slow-moving.

Mid-week then already and Wednesday sees that heavy band of rain reluctantly clearing away south east during the morning but I wouldn’t expect it to clear Kent completely until late morning. It’ll leave behind a pleasant day for all of the U.K and Ireland on Wednesday with plenty of sunshine around, some unbroken cloud and temperatures in the mid to high teens, maybe touching 20°C across the west, pegged back elsewhere by a strengthening north easterly wind. With clear skies we’ll see temperatures drop into high single figures, such a relief from the muggy nights of last week for sure.

Moving onto Thursday and overnight a vertical band of rain will push into Ireland by dawn and slowly cross country reaching Scotland by late morning. Further south and east of this we look to have a better day but that rain will push into North Wales and north west England by tea time on Thursday and then it’ll move south into northern England and The Midlands later on Thursday evening but it’ll be weakening as it does so. That rain across Scotland will slowly clear from the west to leave a showery picture, the same for Ireland.  A strong westerly wind in place will nudge temperatures up into the high teens, maybe 20°C across Wales but it’ll also push showers across the U.K and Ireland through Thursday night into Friday.

So closing out the week we have a continuation of that showery theme for Friday morning but these will clear Ireland through Friday morning and the rest of us through the afternoon, though maybe lingering on in the east on Friday evening. So after the rain moves through, it’ll be a good dry day on Friday for most parts, except the east coast with that lingering rain. Temperatures will pick up into the high teens and low twenties with a moderate to strong north westerly wind in situ.

So how are we looking for the weekend ?

Saturday looks to be potentially wet for Scotland and Ireland with rain pushing in from the north west and moving on a south easterly trajectory through the course of Saturday morning. By Saturday afternoon that rain will lessen in intensity but move into northern England pushing cloud before it across The Midlands and Central England. So a mixed day for Saturday for Scotland, the north of England and Ireland with a wet start giving away to showers and some sunny intervals later. Cloudy and dry I think for England and Wales with temperatures in the mid to high teens again, maybe nudging into the twenties in the south before the cloud cover builds. Sunday sees some rain again for the west of Scotland first off but this should clear to give a better day on Sunday. Warmer for us all on Sunday I think as high pressure nudges across from the west.

Weather Outlook

As stated earlier, I think the accuracy of all weather models from 5-10 days is taking a bit of a beating at the moment. It’s because we are alternating between peaks and troughs in the jet stream and in fairness it’s pretty difficult to predict where the line is drawn across the U.K and Ireland from a vertical and horizontal perspective. But here goes anyway…

So next week looks like starting unsettled, particularly for the north and west as a low pressure system is pushing bands of rain down on a north westerly airstream. So sunshine and showers for us all I think Monday and Tuesday but high pressure gently nudges some more stable weather in from the west on Wednesday so Ireland should clear up first if it’s right. Dry and settled then for the latter part of next week I think with light winds and pleasant rather than searing hot tempertaures.

Agronomic Notes

Ok so continuing the theme of catch up we can now take a look at June from a GDD and G.P perspective using all the data you guys have kindly sent my way, cheers its appreciated.

First off we look at at our yearly comparision using our Thame, U.K location…


If we look at the monthly data we can see June 2017’s total of 329.5 for monthly GDD is the highest total we have measured over the last 7 years, some 20% higher than any other year.

Because I am ultimately sad weather-wise, I ran some numbers for 1976 which some of us will remember as being the year of the drought and continual high temperatures and June 1976 comes out at 320 GDD, so we topped that in 2017 !

Now as stated last month just because we have high GDD in the summer it doesn’t necessarily translate to more growth because we know there’s a point where grass growth drops off depending on the species we are dealing with.

Anywhere north of 26°C and Poa annua just battens down the hatches whilst bentgrass is quite happy. Perennial ryegrass I think begins to slow down from a growth perspective above 30°C and temperatures of 38°C are capable of killing it outright. On that note it’s not inconceivable over the last month that on sheltered areas in full sun we have hit the maximum threshold level for Perennial Ryegrass.


Looking at the cumulative y.t.d, we can see that 2017 continues to be our warmest year since we started doing year-on-year comparisons from a GDD perspective, 17% higher than the last warm year in 2011.

U.K Site Comparison – June 2017


Plenty of data this month and it’s interesting to see that the areas receiving the highest rainfall were in the south west of England and Scotland, eastern Scotland and York. Unusually there has been quite a few occasions this summer when the main rainfall fronts have moved up the east coast and so a usually dry area of the country is amongst the wettest over the last 6-8 weeks.

The data from Guildford, traditionally one of the highest temperature regions in England shows a total GDD of 349.75, which is amazing and averages out at 11.6 every day….I bet fan and ice cream salesman had a very good June 🙂

Over to Ireland and a look at how June turned out there…


Well from a GDD perspective no suprise to see much lower figures for June 2017, with pretty good consistency across the country, Dublin just squeezing in as the warmest area and Claremorris, the coolest 🙁 Rainfall-wise, further indication that alot of June’s rainfall came from the west and then crossed the country with a pretty wet month all in all. That said….

Monthly totals can be deceptive…

If you look at monthly stats, particularly rainfall, you’ll see some high monthly totals, 100mm for Devon, 92mm for Dublin and the like and it would suggest plenty of rain across the month, but that’s where looking at monthly stats can be deceptive…


You can see when we overlay the daily rainfall pattern that most locations received nearly 50% of their monthly total across two days, one at the beginning of the month and one at the end. There was also a period of nearly two weeks when no rain fell at all so June 2017 may have been a wet month in some locations but it was also a droughty one from a plant’s perspective with a prolonged period of stress..

G.P data pinpoints summer stress…


The graph above shows the maximum air temperature in Guildford across the month peaking with 5 days in excess of 30°C from the 17th June to 22nd June. You can see the corresponding dip in G.P during this period as it falls back dramatically. This is highlighting a period of intense plant stress due to high temperature and high daily loss of moisture from the grass plant.

It was during this period that many issues become apparent, not least with irrigation and organic matter.

Thatch is concentrated organic matter and as such heats up far quicker than an organic matter / soil mix and therefore during periods of high temperature, areas that contain more organic matter tend to show plant stress much more quickly.. They also display a tendency to become hydrophobic more quickly as well and this adds further to plant stress. During this period it was not uncommon to find areas on turf surfaces with high organic matter showing pronounced hydrophobicity and rootzone moisture levels less than 5%.

Irrigation is a multi-component discussion and quite individual to location, system design and personal irrigation preference but it’s clear that these kind of conditions highlight weak irrigation performance. This can be down to poor head coverage, incorrect application of water (too little or too much), incorrect balance between mains irrigation and hand-watering to name but a few.

More often than not it can also be down to under-estimating how much moisture is being lost from the rootzone and having no clear concept how much you’re applying, to where, at the same time.

Measuring irrigation in run time rather than mm applied is the first mistake.

Thankfully if you’re able to afford one, a moisture meter is a great way of more accurately understanding how much water is getting to where on your turf surface so you can then dove-tail run time and resulting soil moisture levels. The missing part of this equation is Evapotranspiration (E.T) and this parameter approximates how much moisture is being lost from the rootzone. Now I accept a lot of facilities don’t have the luxury of affording a weather station with E.T measurement but you can get an idea of your local E.T by looking at forecast data.

During this stress period in June, we consistently ran high daily E.T’s > 5mm per day and over that 5-day period it wouldn’t have been unheard of to have lost 30mm of moisture from the rootzone.  Even if you’re replacing 50% of this by a combination of irrigation and hand watering, you’d need to apply 15mm of water over the 5 days just to keep the grass plant ticking over.

The coming week….

Moisture and cooler nights over the coming few days following on from a warm period of weather will no doubt trigger some more disease pressure, notably Superficial Fairy Ring, Microdochium nivale and possibly Waitea Patch. We may also see the first signs of Dollar Spot and Anthracnose.

We chatted about this one last week but we have also seen some really odd Rhizoctonia symptoms spring up lately with the combination of high temperature and humidity (note without more detailed analysis it is difficult to pinpoint exactly which species of this disease is responsible in the image below but Waitea is suspected).

This patch below shows not only some turf loss but arial mycelium typical for Rhizoctonia species…


The respite from the heat plus some natural moisture will give the grass plant a chance to take a breath so why not help it with some micro-solid tining or vertidraining to facilitate good gaseous exchange and allow moisture to move more freely from the surface. The benefits of summer vertidraining with small tines and using a lightwieght machine will be clear to see in the coming months.

Ok that’s it for this week, all the best for the coming week.

Mark Hunt