Those warnings continue into Thursday for much of Wales, the South West, North West, and north-east Scotland.
George Flinton of the AA said: "Heavy rain and strong wind, coupled with commuting home in the dark, can make for some very hazardous driving conditions".
The yellow warning runs from 03:00 until 15:00 GMT.
Portsmouth City Council said that the event, which was planned to take place from 4pm to 6pm on Wednesday evening, had to be called off because of the high winds and rain.
High seas are also expected, with a risk of coastal flooding.
When and where Storm Diana will batter Britain today
On Thursday, two more warnings for strong winds will cover south-west England, Wales, north-west England and Scotland, where gusts could reach 80mph.
Condor Ferries cancelled the 9am service from the city to Guernsey, the 9am sailing to Jersey, the 5.20pm sailing from Guernsey to Jersey and the 9.20pm sailing from Jersey to Portsmouth because of the windy conditions brought by Storm Diana.
It is threatening the Azores at present and is due to make itself felt over western parts of the United Kingdom from tomorrow. Winds will also turn northwesterly across Northern Ireland later, transferring the main focus to northern areas here. With that, there will be some heavy bursts of rain.
Ireland and Northern Ireland will likely suffer the most significant delays to travel during the morning commute, before winds push east during the daytime hours. "Even away from these areas, we're expecting a very windy start of the day".
"The worst place is on the west coast".
A new cyclonic low, which will span 2,000 miles from the north of France to southern Greenland could be strong enough to warrant another name - Deirdre - before the weekend.
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