Latest ensemble forecasts from the ECMWF and KNMI place Amsterdam’s June 22 maximum near 27–28 °C, reflecting a transitional pattern of weak high pressure and light southerly flow that limits strong warm-air advection while allowing modest daytime heating under broken cloud. Small differences in modeled cloud timing, boundary-layer mixing depth, and the precise arrival of a weak Atlantic front create the tight spread between 27 °C and 28 °C; runs showing slightly clearer skies or stronger insolation push peaks toward the upper end, while increased low-level moisture or earlier cloud build-up favor the lower value. Historical June maxima in Amsterdam average around 20–21 °C, so current guidance remains above climatology but well below heat-wave thresholds. Updated high-resolution runs and the midday KNMI briefing on June 21 will likely tighten the distribution ahead of market resolution.