Total sales in May were marginally up by 0.1% from the same month a year earlier, when sales declined 1.1%.
Like-for-like sales, which strip out factors such as new store openings, decreased 1.2% in May, lower than the 3.2% fall recoded a year ago.
Food sales grew from year-ago level, but volumes are likely to have fallen slightly when food inflation is taken in to consideration.
Warm weather at the end of the month helped boost apparel and footwear sales, as well as sales of summer foods.
Big-ticket purchases, however, continued to struggle and were often promotion-led, amid continued consumer caution.
The organisation said on both like-for-like and total measures, retail sales were much weaker than for the whole UK.
Scottish Retail Consortium director Ian Shearer said a welcome spell of warmth at the end of May helped lift these figures but the burst of summer didn’t bring a boost on the scale enjoyed elsewhere.
"The underlying picture remains weak, showing sales falling in real terms for the sector overall, and this is particularly worrying given that they are being compared against poor figures for May in 2011," Shearer added.
"Consumer caution persisted, household budgets are still under severe strain and most shoppers are committed to buying only what they consider to be essentials.
"Food retailers had a brighter month with changes in consumer preferences reflecting the shift in temperatures. Demand for roasting joints and soups turned into sales of salad and barbecue meats for the final week.
"Other stores, with supplies of summer fashions, outdoor leisure gear and gardening equipment currently languishing in stockrooms, badly need a more prolonged period of summer weather in the coming months to begin to ease the gloom."