Weather tracker: high pressure over western US likely to spread east

Unusual US heat expected to stay, while Canada braces for Arctic blast and Canary Islands endure Storm Therese The intense heat that has dominated much of the US over the past week shows little sign of easing over the coming days as high pressure continues to be anchored across the western half of the country, and this is likely to spread towards the east coast by Thursday. In Phoenix, Arizona, temperatures are expected to remain rooted in the high 30Cs this week after the city experienced a record-breaking 40.5C (105F) on 20 and 21 March. Such readings are highly anomalous for March: the last occurrence of 100F, or just under 38C, here in this month dates back to 1988. The National Weather Service said the threshold was typically not reached until late May, highlighting the unusual intensity of this event. Record-breaking temperatures have been recorded widely across the western US as the daytime maxima exceed 15C above the climatological norm. In Denver, Colorado, the typical March daytime maxima is in the mid-teens Celsius, yet on Saturday temperatures reached 30C. This was the first time 30C had been reached and the city’s highest March temperature since 1971, when 28.9C was re