Brontoskopos

Last week’s outlook ran a touch warm across the board — forecast highs were consistently 1.1 to 1.5°C above what actually verified, so if anything treat the hot numbers below as more likely to undershoot than overshoot, going by recent form.

The big story this week is a genuine changeover. We open in a stubborn, unusually hot ridge — Monday and Tuesday both push into the mid-30s, running roughly 8-9°C above the seasonal norm for early September — before the pattern breaks down by midweek as zonal flow reasserts itself and the jet swings closer. That knocks temperatures down into the low-to-mid 20s by Thursday onward, with a real rain-bearing system passing through Wednesday-Thursday, and then a quieter, comfortably dry weekend. It’s a genuinely two-faced week: brutal heat first, then some of the nicest air of the whole month once it clears out. The week averages out to a 6.3/10, which undersells how good the back half actually looks.

Monday (34.8-22.8) — 3/10: Brutally hot and humid, running about 8 degrees above the seasonal average — the heat is the whole story here. An isolated storm or two can’t be ruled out in the afternoon, but don’t expect it to break the heat. Rough one.

Tuesday (35.4-21.1) — 3/10: Even hotter, near 9 degrees above normal for the date and confidently so — this is a legitimate heat day, feels-like temperatures near 37°C. Humid again with an isolated storm or two possible, but the heat dominates regardless of what falls.

Wednesday (31.3-22.5) — 5/10: Still warm and humid, likely near 31°C, but a more organized round of storms looks possible as the pattern starts to turn — about half the ensemble members are flagging measurable rain. A step down from the weekend’s extremes, though still sticky.

Thursday (23.9-18.4) — 6/10: This is where the pattern really breaks — confidence is low this far out, with guidance spanning anywhere from the low 20s to around 30°C, but the consensus point is a proper cooldown to near 24°C. Rain looks like the headline, with a median take of around 10mm and a range of 1.9 to 13.6mm — an isolated storm can’t be ruled out on top of that.

Friday (24.4-16.5) — 9/10: Guidance disagrees on the exact number, anywhere from 24°C to 27°C, but either way this looks like a lovely, noticeably drier day after the midweek mugginess. Plenty of ensemble members flag some rain, though the median outcome stays close to dry. Yes, it’s very good!!

Saturday (24.6-15.5) — 8/10: Confidence is low, with modelled highs anywhere from the low-to-mid 20s, but comfort should still hold up nicely. Rain chances are modest (around 30%) though a few members go big, with a possible range up to 23.7mm if the wetter solutions verify — worth keeping an eye on, but the most likely outcome is a fine day.

Sunday (25.4-14.4) — 10/10: Confidence is low on the exact numbers this far out, but the shape is clear — comfortable dew points, a cool 14.4°C low, and only a slim 16% chance of any rain. The pick of the week, easily.

The fortnight at a glance

Week two

The zonal, slightly-above-normal pattern looks to largely hold into days 8-14, if the ensembles are right, with likely highs mostly in the low-to-upper 20s (roughly 23-29°C most days) and only mild warm anomalies of a degree or two above climatology. Rain chances stay modest through the middle of the stretch but trend upward toward the back end, with the precipitation member fraction climbing from around 0.2 early in the period to closer to 0.35-0.4 by September 18th-20th — hinting at an increasing, though still far from certain, chance of wetter weather as the second week wears on.

Tl;dr: Brace for a brutally hot Monday-Tuesday near 35°C, then ride out a rain-bearing changeover midweek into a genuinely lovely, cool, low-humidity weekend from Friday onward.

Weather data by Open-Meteo.com. Models: ecmwf_ifs025, icon_seamless, gfs_seamless, meteofrance_seamless, best_match. Generated 2026-09-06 07:02 CEST. This is a hobby forecast, not a substitute for official ARPAE / Protezione Civile warnings.