SYDNEY, Oct 21 (Reuters) - U.S. wheat futures rose for a fifth straight session on Wednesday as concerns about adverse global weather pushed prices towards a near six-year high.

FUNDAMENTALS

* The most-active wheat futures on the Chicago Board of Trade were up 0.4% at $6.34-3/4 a bushel by 0159 GMT. They closed up 0.8% on Tuesday when prices hit a December 2014 high of $6.48-1/4 a bushel.

* Soybean futures were up 0.5% at $10.69 a bushel, having firmed 0.9% on Tuesday.

* Corn futures were up 0.2% at $4.09-3/4 a bushel. Corn gained 0.9% in the previous session.

* Long-awaited rains arrived in some parts of Russia's winter wheat-sowing regions over the weekend after a spate of dry weather, but more were still needed, Dmitry Rylko, the head of the IKAR agriculture consultancy, said on Monday.

* The U.S. Agriculture Department on Tuesday morning said that private exporters reported the sale of 132,000 tonnes of soybeans to unknown destinations.

* It was the sixth day in a row the USDA has reported a so-called flash sale of either corn or soybeans.

MARKET NEWS

* The dollar was pinned near a one-week low on Wednesday as investors optimistic about the prospects for a pre-election U.S. stimulus package sought riskier currencies.

* Oil prices fell after a surprise climb in U.S. crude stockpiles added to concerns about a global supply glut as a spike in global COVID-19 cases fuels demand fears and production returns in Libya.

* Asian stocks were set for modest gains after renewed U.S. stimulus hopes helped Wall Street higher, although wobbles in the tech sector could keep a lid on investor sentiment.

(Reporting by Colin Packham; editing by Uttaresh.V)