* First half pretax profit drops 32 pct year-on-year
* Analysts estimates were about 5 mln euros higher
* Gross premiums fell 4.8 pct to 5 bln eur (Adds details on severe weather payouts)
FRANKFURT, Aug 29 (Reuters) - First-half profit before tax at Vienna Insurance Group fell 32 percent, weighed down by a spike in payouts for severe weather claims and an impairment at its business in Romania.
Emerging Europe's biggest insurer generated pretax profit of 205.7 million euros ($274.4 million) as premiums fell 4.8 percent to 5 billion euros, mainly due to a reduction in its single premium business in Poland.
Severe weather claims tripled to about 230 million euros mainly because of flooding on the Danube in June, which hit Germany, Austria and the Czech Republic.
Vienna Insurance last week announced a 75 million euro writedown of goodwill to reflect a more pessimistic view of prospects for its non-life business in Romania.
The company said its combined ratio - a key measure of profitability - remained below 100 percent, which means it is covering costs.
Analysts polled by Reuters had on average expected second-quarter pretax profit to fall by two-thirds to 51.5 million euros on lower premiums of 2.28 billion, or first-half pretax profit of 210.9 million based on a first quarter at 159.4 million. ($1 = 0.7496 euros) (Reporting by Edward Taylor; Editing by Louise Ireland)