The 64-year-old's work ethic and stamina during late-night negotiations has become the stuff of legend since she became chancellor in 2005.
The first, in mid-June, was during a meeting with Ukrainian President Volodymyr Zelensky but Merkel's team assured those concerned that she was just dehydrated and had recovered after drinking a glass of water.
German Chancellor Merkel later addressed this newest episode herself saying that she felt fine and there was no reason to worry. Temperatures were much cooler that day, as they were on Wednesday.
"I will have to live with it for a while", added Merkel, who turns 65 next week.
The second incident over a week later, which occurred indoors, she tried to explain with a psychological disposition.More news: Nintendo Switch Lite revealed, launching September 20
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"I think my statement that I am fine can find acceptance", she continued. "I said recently that I am in a phase of processing the last military honours with President Zelenskiy". "That is apparently not yet completely finished, but progress has been made", she added.
"I feel very well, ' she said".
In the United States, portions of the results of the president's annual medical examination is traditionally made public, but in Germany, political leaders are generally expected to enjoy more privacy around their health. It is not publicly known if Merkel has any health problems. She later blamed dehydration for her shakes.
Merkel demurred when asked at Wednesday's news conference whether, given recent concern about her health, she should now take a more head-on approach to the issue.
Her spokesman later said she was OK and would attend the G20 summit in Japan. "Beyond that, I'm firmly convinced that I'm very well capable".
A spokeswoman for Merkel, Ulrike Demmer, declined to comment on whether there had been any other shaking episodes beyond the three publicly known ones.
She has come under pressure to step aside after the ruling parties did poorly in European elections in May and her coalition threatens to fall apart.