Moscow — A senior Soviet official says this year's Soviet grain harvest is ''significantly'' higher than last year's despite some late-season weather problems, and might well surpass the United States' estimate of 200 million cubic tons.
The official, a prominent member of the Soviet Communist Party Central Committee, made the prediction during an hour-long interview in which he also said he thought the US invasion of Grenada might well hurt President Reagan politically.
His remark on the grain harvest seemed to promise further good news for Soviet consumers - who have already seen the meat and dairy-product shortages of the past few years erode significantly after a stronger animal-fodder crop last winter.
And if the prediction is borne out - the official said no firm figure for the harvest could be given yet - the overall grain crop will be the best in four lean years marked by huge grain imports.
''Judging by this year's results,'' the official said while replying to a general question on the shape of the Soviet economy, ''we are on the right track in agriculture.
''We have a significantly bigger harvest this year, despite some weather problems'' - a reference, in part, to late-season rains and generally tough harvesting weather in parts of Siberia and of the Asian republic of Kazakhstan.
So disappointing were the last two years' Soviet harvest - the official annual target figure for the current five-year plan is 235 million tons - that the totals were never announced.
The US estimates that last year's harvest was about 180 million tons, and that the previous year's was a mere 160 million.
When asked whether it would be fair to assume last year's figure was about 180 million, the official nodded.
''I can give no specific figure for this year yet,'' he said. ''But I think it will be more than 200 million tons.''
An American estimate of this year's crop, issued before the recent weather problems, predicated a figure of 200 million.
Agricultural attaches in foreign embassies here said it was indeed likely the weather problems, at least so far, had not sharply dented the overall crop. This , they explained, was because the total of unharvested acreage affected did not appear to be devastatingly large.
Growing and harvesting of grain in the Soviet Union, a large portion of whose territory lies in forbidding northern latitudes, has perennially been complicated by the weather. It has also been snagged by pervasive inefficiencies and by a shortage of vital infrastructure: good roads, storage and transport facilitites, refrigeration apparatus, and the like.
Even in lean years, the Soviets produce enough grain to give their people bread. The pinch is felt in animal feed and thus, ultimately, in supplies of meat and dairy products.
The Soviets' large grain imports have been designed to meet those needs. The country's relatively quick rebound in production of meat and milk - up sharply this year - has been due partly to imports. But Western experts here note the Kremlin also wisely avoided ''distress slaughter'' of Soviet herds - letting them grow lean instead - and have thus been able quite quickly to fatten existing livestock.
The immediate future would seem to look relatively bright - particularly if the Soviets harvest an overall total of 200 million tons of grain for 1983.
In addition, Western analysts say the country is having its second strong year in a row in the important area of animal feed grains.
The Soviet official also reiterated recent Soviet criticism of Reagan administration policies, terming the intervention on Grenada a further indication of US ''extremism.'' He attached great significance to criticism of the move from various Western allies of Mr. Reagan.
The official said that he tended to think the invasion might seriously hurt Mr. Reagan domestically.