Retail sales growth is expected to be lower than originally expected this month but will still be up year on year, the Opera Solutions Retail Predictor for Retail Week indicates.

Sales growth was originally anticipated to be 1.5% in April (Retail Week, March 16), which was already below the 10-year average of 3.4%.

However, the growth forecast for this month has been reduced to 1%, taking into account ONS revisions to official sales data for the last two months of 2011 and January 2012.

The Retail Predictor forecasts for May and June have also been reduced from 2.95% and 3.6% respectively to 2.1% and 2.8%.

There are also signs of how the Olympics, which open on July 27, are likely to affect sales patterns over the summer.

Opera executive director and Europe lead Ray Eitel-Porter said: “We are beginning to see the expected impact of the Olympics in our forecasts for July and August.”

He observed that stocking up and extended Sunday opening hours during the whole of July may pull sales from August into July.

However, August is expected to drag some retail revenue forward from September. Falling inflation is also likely to affect sales growth this September. The Opera Solutions Retail Predictor has been created using a wide range of data and back-tested against ONS numbers over a 24-month period.