T132 looks very heavy or is it to early to be accurate?

I disagree. If 35.6C was reached in 1906, 120 years ago, then I think 38C is perfectly possible in the first week of September with our current climate.

https://wetterzentrale.de/topkarten.php?map=1&model=ecm&var=18&time=0&run=0&lid=OP&h=0&mv=0&tr=6 

All the water vapour in the northern Atlantic seems to condense out over the course of a week!

I see what you mean! We become the Atlantic after being the Sahara.

Probably - it has been for 2 years now!

Let's just hope it all condenses over Essex!

https://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&lat=57.2&lon=-3.5 

MetO chart (has BBC switched back to them yet?) seems to show rain moving up from France, fragmenting into showers when it reaches Britain, and then skipping over the south to intensify in the north!

I wouldn’t hold your breath. 

In our neck of the woods El Ninos (and La Niña) do not start taking effect, if any until approx 4-6 months after the event builds enough strength to be officiated. 

Nonsensical comments about an ‘El Nino August bank holiday monsoon’ are nearly as daft as My Blobby himself. 

Quite a change this morning runs the cooler weather due to arrive after 28th now had been push back and warmer 850's slowly extended to over 8C was 5-6C for the BH weekend   Also look much drier with few spikes no more than 2mm.  This changes due to the E Med which was going for 25-26C 850s over the last few days of August had been cancelled and drop it to 20C witth quite few member go down as low as 16C with welcome rain spikes appeared for Nicosia.  I use Nicosia, Nuneaton and London ensembles to view so when E Med get cooler here get better normally and a good guidance.

https://wetterzentrale.de/en/show_diagrams.php?geoid=49069&model=aifs&var=2&run=0&lid=ENS&bw=1 

GFS Op 00z - agrees with FAX; the last of the above LPs arrives in N Ireland 100mb Mon 31st. Then a week of standard westerlies, unsettled in the north, fine in the south, before a deeper LP 985mb Western Isles Sun 6th causes a general drop in pressure. Finally the ex-hurricane (on a different track each day) adds to the circulation of this LP and, although filling, extends the drop in pressure southwards to affect S England as well.

ECM - similar to GFS but fits in an extra LP 995mb Irish Sea Wed 2nd before the westerlies appear.

AIFS - London, maxima 24C Wed 26th before slipping to 18C Tue 1st, then a recovery to 23C Sun 6th. Rain every day for a week starting Wed 26th, no great amounts. Edinburgh, briefly 20C then 15-18C through to Mon 7th. Rain, slightly heavier than London, every day from Fri 28th.

GEFS - mean temp has good ens support to Tue 1st then a spread develops. Mean a couple of degrees above norm for the next 2-3 Days then close to norm to Wed 9th (op a cold outlier at the end). Rain in most runs on most days from Wed 26th (Scotland from 27th), heaviest early on, less probable later in the S and W but remaining heavy and persistent near NE England.

The Met Office app shows no more than a 50% chance of rain this week IMBY. That can change of course but until it shows 100% I'm not optimistic for meaningful rain here.

Is it? Looks like torrential downpours possible from Wednesday onwards

The rain spikes are certainly getting smaller with most passing run. Take London for example, which looked much wetter only a couple of days ago:

https://wetterzentrale.de/en/show_diagrams.php?geoid=49069&model=gfs&var=4&run=0&lid=ENS&bw=1 

Then hints of a pressure surge for the start of next month continues to be modelled:

https://wetterzentrale.de/en/show_diagrams.php?geoid=49069&model=gfs&var=23&run=0&lid=ENS&bw=1 

When you get these lows coming up from the south they are a forecaster's nightmare. There is usually no traditional frontal rain, just showery stuff that just might or probably won't give rain to places that need it. (MBY) Then as the low trundles north, it regenerates for some reason that I've never been able to understand and dumps copious amounts of rain further north. I'm placing my hopes for the second low to deliver rain IMBY. But I won't put money on it. Last night's showery stuff, for what it was worth, came across from France and then gave up the ghost in the Channel. It's done this so many times in the past few years.

There was many wet outliers now being removed just near flat lines and never more than 1 or 2mm or rain from showers.  Strange other side all about rain hopecasting posts and unsettled weather but no interest with this week warm weather which will be 25C on the app mean mid to high 20's by tomorrow peak then a slight drop to still above average.  Some hints of warm up in early September so need to see at trend to be warmer to hot and longer lasting one.

GFS Op 00z - agrees with FAX although the LP Thu 27th extends a more definite trough NE-wards. Then that LP on the 29th moves across  N England 1000mb Sun 30th initiating a week of westerlies, unsettled in the north and fine in the south.  On Mon 7th, the latest track for the ex-hurricane takes it to Cornwall, only 995mb by then, running away SE-wards with a general pressure rise behind it. 

ECM agrees with GFS to Fri 4th when the ex-hurricane is already not too far off in the Atlantic, weaker than on GFS but with enough influence to turn winds into milder/warmer and likely humid SW-lies rather than W-lies.

AIFS - London, maxima soon dropping to 20-21C (a couple of days warmer 4th/5th), limited amount of rain every day to Wed 2nd then drying up. Edinburgh, maxima 16-18C, also with warmer days Wed 26th and Fri 4th; rain on most days from Fri 28th but brief drier slots Thu 3rd and Mon 7th.

GEFS - mean temp with good ens support for the first week, and not too bad after that; a little above norm for the rest of this week, then close to norm (op & control on the cool side after Sat 5th). Rain from one run or another on most days to Thu 10th, probably heaviest this week but no easily summarisable trend.