Update 11.30am Thursday:
Power has been restord to all but two homes in Rainbow and two in Coonooer Bridge, with both outages caused by lightning strikes. Both outages are expected to be resolved by 2pm.
The haystack fire warning for Lascelles residents has also lifted.
Update 6.30pm Wednesday:
The storms have moved on from the Wimmera and Grampians regions.
Ben Nevis, near Ararat, has received the most rain of anywhere in Victoria since 9am, with 18.4mm.
The latest weather warning suggests the storms have moved east away from Horsham, but will continue to affect Stawell, parts of the Grampians and Ararat.
A 96 km/h gust was recorded at Ben Nevis at 3:26pm.
BOM senior forecaster Richard Russell says the storm front will move slowly eastward over the next few hours.
He says Central Victoria and Melbourne will experience storms in the early to mid evening on Wednesday.
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Stawell has received 11.2 millimetres of rain since 9am, and Horsham 2.4.
Power remains out to more than 170 customers between Ararat and Kaniva.
Power is out to 178 customers across the Wimmera and Grampians and a lane of the Western Highway was briefly blocked, following lightning storms in the region.
Powercor expects to have resolved the outages by 7pm.
A State Emergency Service spokeswoman has said units across the region have received three callouts since 7am, and seven in the past 24 hours.
"At 11.44am today there was water coming into a Balmoral nursing home through double doors out the back," she said. "There was five sandbags required and the job was completed at 12.30pm.
"There was a tree down on the highway at Dadswells Bridge blocking a single lane at 11am, and the tree was removed with assitance by the SES at 11.42am.
"The only job for Horsham in the last 24 hours was a road crash rescue in Dimboola. It's a matter of people paying attention to the warnings and reporting o the SES whether their local creek has had its banks break."
CFA District 17's Wayne Hirst said the Lascelles haystack fire had consumed 600 bales, and crews were letting it burn out.
"There is smoke downwind of where the fire is burning, so if peope have problems with the smoke they should keep their windows and doors closed," he said.
Another haystack fire is burning on Rosebery East Rd, Beulah. Residents within 100 kilometres are being given the same advice as those near the Lascelles fire.
CFA and DELWP crews across western Victoria has responded to half a dozen incidents today.
Mr Hirst said there had been a small grassfire and power outage at Crymelon. "Powercor was requested to attend so possible it might have been a electrical fault with a power supply. It may have been lightning strikes that caused it," he said.
CFA crews also repsonded to a small grass fire at Yanac, which has also been declared safe.
Mr Hirst said DELWP crews are on scene at a bushfire in Yallakar State Forest southwest of Edenhope which is under control
A slow moving low-pressure trough crossing the state likely to result in severe thunderstorms today.
Severe thunderstorms are likely to produce damaging winds and heavy rainfall that may lead to flash flooding in the warning area over the next several hours. The threat area is likely to expand to the east and south during the afternoon. Locations which may be affected include Mildura, Swan Hill, Walpeup, Horsham, Stawell and Warracknabeal.
The State Emergency Service advises that people should:
* Be aware that trees that have been damaged by heat or fire may be unstable and more likely to fall when it is windy or wet.
* Be aware that in fire affected areas, rainfall run-off into waterways may contain debris such as ash, soil, trees and rocks.
* Be alert that in areas recently affected by fires, heavy rainfall increases the potential for landslides and debris across roads.
* Check that loose items such as outdoor settings, umbrellas and trampolines are safely secured and move vehicles under cover or away from trees.
* Stay indoors and away from windows.
* If outdoors, move to a safe place indoors. Stay away from trees, drains, gutters, creeks and waterways.
* If driving conditions are dangerous, safely pull over away from trees, drains, low-lying areas and floodwater. Avoid travel if possible.
* Stay safe by avoiding dangerous hazards, such as floodwater, mud, debris, damaged roads and fallen trees.
* Stay away from fallen powerlines always assume they are live.
* Stay informed monitor weather warnings, forecasts and river levels at the Bureau of Meteorology website, and warnings through VicEmergency.
9.20AM: Horsham has received almost two millimetres of rain in the past hour, and Longerenong more than three.
It is not the only sudden downpour the region has experienced in the last day, with Edenhope receiving 5.2 mm between 4.30 and 5am.
Emergency Management Victoria has update it's advice for Hopetoun, Lascelles and Woomelang residents about a haystack fire on Gama-Sea LakeRd.
It says while crews are attending the fire, it may continue to burn for a number of days. There is no immediate threat to the community and no action is required.
EARLIER: Country Fire Authority crews have brought a tree fire under control in Apsley this morning, after storms brought lightning to the region overnight.
A spokeswoman said crews from Apsley and Bringalbert South were called to a paddock near the town at 5.41am.
"Crews remain on the scene and they have asked for a bulldozer to come and fell the tree," she said. "We don't know what may have caused it, but it's under control and it hasn't spread beyond the tree."
An SES spokesman said the region had not received any calls for assistance during the storms overnight.
"Three crews were also called to Laharum at 4pm to a burnoff that had become out of control. The fire burning in two hectares of dry grass and was brought under control 15 minutes later."
Then at 8.40pm, fire crews were called to an incident at Horsham Plaza, which turned out to be a false alarm.
"A build up of dust in an air conditioning duct prompted a fire indicator panel to go off," the spokeswoman said.
A warning for a haystack fire near Lascelles remains current.
Reports say there have been just under 5,000 strikes of lightning within 200 kilometres of Stawell in the past 14 hours.
There was some rain with the storms, most of it falling on Edenhope (11.8mm since 9am Tuesday), Nhill (4.6) and Warracknabeal (4.4).