Kim Bromwich has kindly supplied the following account from the Welwyn Parish Register:
Feb: Sunday 28. There was very hasty thaw and flood: and in the middle of Monday night following; Welwyn town was overflowed by the River (Mimram); and the houses in the lower rooms were flooded four and some near five feet deep in water.
At the bridge, a chimney was drove down, and another damaged so much as it was obliged to be propped from falling, and part of the room and some things in it were carried away down the river to the Mill.
The water ran along the Turnpike road, by the houses thro' the Rectory Farmyard into the Mill-Lane, driving away the pales as it went along, and carried away the Miller's out offices, passing thro' the house, threatening destruction to that and the Mill; and two horses were near being drowned in the Miller's stable, but were saved by two men going up to their arms in the water, who with great difficulty got them out.
The Tanner's yard was filled with water and the Bark much damaged in both his barns.
The Arches, leading in off the road in and out of Lockley's Pleasure - Ground before the House were blown up, and a Gentleman's (Mr Willis Rector of Tewin) Servant lad and horse were very near being lost in the water; the lad was drove into the hedge and drawn out by the help of ropes thrown to him; but the horse, by the force of the waters, was carried far into the meadows, and obliged to be left there all the night, and with much difficulty was recovered the next day.
The river Lea also overflowed in Brocket Hall Park, drove down the pales into the mill orchard, carried away a part of a Hay-stack and the yard gate and forced up the gate post, undermined the foundation wall, took away corner of the mill room, and damaged the wheat sacks standing in the room; blew up the arch at the park-gate, washed away the gravel from under the groundsell, and left it quiet clear, and forced down the Park-wall several yards in length; carried away the miller's yard, gate and hay to the bridge, stopped the arch, and blew up the Bridge, so that nothing could pass over it. The waggons went by-way along the side of the river to Hatfield; and the coaches, chaises, and horses were permitted two days to pass thro' the park, till a temporary bridge was made of wood. A man from the turnpike gate was placed at the Lodge near the Park gate to take the tolls of those, who passed through.
A Higler had his Cart-hovel, cart and Hog-stye carried away into the meadows; and the lower rooms of the houses near the river were filled with water.
The bridge was oblig'd to be entirely pulled down and rebuilt, and even the very foundation was made new again.
The old (or First) Lemsford Mill Bridge cost----- £222.16s 0d It was contracted for £145 and the rise allowed in Bricks was 40 pence per 1000 £ 77 16s 0d
It would appear that the River Ver was also flooded as the following entries appear in the Session Records of the Liberty of St Albans, as reported in Herts County Records, Volume 4
[Easter Sessions, 1795] Order for the erection of a bridge at Frogmore in the parish of St Stephen, of a plain brick bridge, with one arch of thickness of 18 inches, the span of which is to be 18 feet; the bridge is to be 12 feet clear in the carriage way, with brick battlement and oak coping. It is stated that the late floods have washed away and destroyed the former bridge. [Session Books II/70]
[Midsummer Sessions, 1795] Order for the rebuilding of the bridge at Frogmore, at a cost of £75 10s 0d., according to the estimate of Thomas Chambers, of St Albans, bricklayer, except that the coping is to be of stone and not of oak. It is agreed that the sum of £8 to be allowed by the said Chambers for the material of the old bridge, destroyed by the late floods, shall be paid by him to the surveyors of the highways of St Stephen's parish, "in consideration of the expense they have been put to in making a temporary way until such time as the said bridge is re-built." [Session Book II/87]
During the Epiphany Sessions, 1796, the accounts for the building of the Frogmore bridge were paid.
The winter of 1794/5 gets a comparatively long report on Meteorology at Bracknell - Historic Weather Events: [site no longer accessible - for alternative reference see Netweather.]
The winter of 1794/95 was exceptionally severe, with the very cold conditions setting in on Christmas Eve 1794. The frost then lasted, with some breaks, until late March. The cold was most intense during January, which resulted in the coldest January in the instrumental era (as assessed by CET measure/series begins 1659). The February value of 0.8degC was 3.0C below the long-term mean. On the 23rd, the Severn was frozen and so was the Thames, with the usual 'frost fairs' being set up there. On the 25th January, an extreme temperature of (minus) 21 degC (converted from degF) was recorded at an unspecified location in England. A rapid but temporary thaw, accompanied by heavy rain began on the 7th February. This resulted in much flooding across large areas of (at least) England - extensive damage to bridges. The severe cold returned after February 12th, and (as noted above), continued well into March. ...
If you can add to the information given above tell me.