After Britain endured its wettest start to summer on record, the last thing visitors to the Olympic Park may have been expecting was for blazing sunshine to disrupt their travel plans on Tuesday.
But with temperatures in London reaching an unusually high 86 degrees Fahrenheit, rail chiefs were forced to cancel a handful of trains due to stop at the Stratford International station next to the Park and impose speed limits on others further up the line.
That led to minor delays on the main rail line out of northeast London, although the impact on passengers going to the Olympic site was said to be slight.
The opening ceremony for the Games is on Friday and most of those currently using Stratford International to access the Park are media, volunteers and arriving athletes and officials.
Network Rail, which operates Britain's rail infrastructure, put the problems down to older sections of the overhead power lines expanding and sagging in the heat.
"As a result, it is necessary to reduce speeds in order to avoid damaging the equipment and trains," it said.
Nine trains out of a daily total of 1,900 on that line were cancelled and other services suffered delays of a few minutes.
That level of disruption is nothing to the average London commuter accustomed to regular battles with everything from signal failures and delays caused by leaves on the line and the wrong type of snow.
Transport has been one of the biggest challenges for the Games' organizers. Doom-mongers have long warned that the capital's often congested roads and railways will grind to a halt when the Games begin.