Londoners who have struggled to work in record heat now face Tube strikes causing more travel misery.
The RMT union is planning two 24-hour walkouts by Underground drivers on Tuesday June 2 and Thursday June 4.
The dispute with Transport for London (TfL) is over a voluntary four-day week for drivers who earn around £75,000 a year.
Unlike the industrial action in April, the looming strikes will not run midday to midday to impact on two days.
But TfL is warning that there could still be disruption to the Underground network on the mornings of Wednesday June 3 and Friday June 5.
If the walkouts happen, they are expected to impact many lines but at least temperatures will have dropped from the record high, of around 35C, this week.
The forecast for June 2 is 22C, with cloud, light rain showers and sun, and for June 4 a similar outlook but slightly colder at 19C.
The RMT union ditched two planned strikes in May and talks are due to take place this week to try to avert the walkouts by drivers due to take place in early June.
A Transport for London source said: “We are having regular meetings with the RMT to try to resolve the dispute.”
London Mayor Sir Sadiq Khan has urged TfL and the RMT to get around the table to find a solution to avoid commuters and other Tube users having to suffer more disruption on the network.
There were also signs that support for the RMT industrial action may not be as solid as in some previous walkouts.
More than 50% of services on the Underground ran during the April strikes.
The number of trains that were operating also showed that some RMT drivers had turned up to work.
The RMT may be in a weaker position than normal with its industrial action as the deal which it has rejected has been strongly backed by the Aslef train drivers’ union.
Finn Brennan, Aslef district organiser for the Tube, stressed to its members: "The introduction of the four-day week will be the biggest improvement in working conditions for Underground train drivers in decades.
“It means you will have working conditions that are as good as, or better than, those on any mainline train company."
Aslef has highlighted the benefits to its members as including an extra 35 days away from work a year, average weekly rostered hours being cut to 34 from current average of 36, as well as more time at home and less time travelling to and from work, reducing fatigue and giving drivers a better quality of life.
It also stressed that the voluntary deal would make it easier to arrange roster patterns to block leave together, or take long weekends or mini-breaks, and would save money on travel and childcare costs.
Drivers would also for the first time be allowed to volunteer for overtime which would be paid at time and a quarter.
But the RMT (the National Union of Rail, Maritime and Transport Workers) said its members saw the deal on offer as a ‘fake four-day week’ that amounted to five days’ work compressed into four.
It argued that it would mean reduced flexibility over shift patterns, with the potential for only 24 hours notice of what shifts drivers would be doing.
The union also said there were serious concerns from its members about shift length and resulting fatigue impacting safety in a safety-critical role.
TfL has stressed that no driver would be forced to accept the four-day week, as it was voluntary, and it aimed to improve their work-life balance, while improving the reliability of services.
