The May 2026 CDD at Heathrow and Paris were prohibitively warm! A whopping 61 CDD was observed in Paris due to a record (May) heat spike compared to 12 and 15 30-year/10-year climatology. The June 2026 CDD forecast for both Heathrow and Paris remain hot with strong increases in CDD count from the previous (May) forecast. Note that May, June, and July (Paris) are hotter (CDD) forecasts than last year’s totals.

An immense heatwave south and west of Europe is intensifying, typical of the past 10 years during June in this region. The MHW is well-correlated to a summertime 500 MB hot/dry ridge across Europe forecast by ECM "weeklies" in the week 3-4 outlook. Meanwhile, an intense Madden Julian oscillation has caused southern oscillation index into an extreme negative phase signaling the onset of an El Nino climate. Forecast models indicte risk of important cold into Brazil in the 11-15-day period.

The mega-cluster ensemble combining ECM, CFS, and CMC output indicates risk of significant cold not far from Brazil coffee-growing areas on June 15-16.

The Madden Julian oscillation has ignited across the equatorial Pacific Ocean likely to remain intense during the next 2 weeks (Fig. 1). The outlook indicates MJO is withing phase_7 implying a cooler East U.S./warmer West U.S. thermal regime with wet weather biased toward the southern states. Additionally, MJO phase_7 is supportive of a developing El Nino climate as demonstrated by recent and an intense negative southern oscillation index.