It always fascinates me how much the weather affects life for retailers.

For instance, a wetter-than-expected summer can spell disaster for retailers who have vast swathes of summer stock, such as barbecues and other outdoor items.

However, the flip-side is that better-than-expected weather can also have a detrimental effect on the fortunes of retailers. An Indian summer, for instance, can mean that winter clothing stock is in less demand, while summer stock has already been sold-off.

So, the beautiful, sunny weather we experienced here in the UK in July could have had a positive or negative effect on retail sales figures, simply because it was out of the ordinary.

I was encouraged to see, however, that sales figures were very positive. Indeed, sales volumes increased at their fastest pace for more than 2.5 years, as shoppers apparently stocked up on food and alcohol during the longest heat wave of the 21st Century.

Retail sales by volume increased by 3% versus July 2012. This is the biggest rise since early 2011, with The Office for National Statistics saying that month-on-month sales improved by 1.1% between June and July, beating analysts' expectations by some degree.

Furthermore, economic commentators now seem hopeful that July's figures can help to provide strong figures for UK GDP in the third quarter of the year, since retail sales figures enjoyed their best three-month period in five years.

So, how can Fools like us take advantage of such positive growth figures?

One way is to buy shares in Marks & Spencer (LSE: MKS) (NASDAQOTH: MAKSY.US). The reason I've picked Marks & Spencer is that it is highly focused on the UK, as well as offering a respectable yield and growth prospects.

Indeed, while many of its peers are hell-bent on international expansion, M&S seems to be getting its UK operations in order before further expanding abroad. The reorganisation and rationalisation of UK stores is well under way, with the company seeking to be more reactive to temporary changes in customer demand than it has been in the past.

In other words, M&S is seeking to be more 'on its toes' than it used to be; making itself more relevant to what customers want. This is good news for investors because it means a fresher, more customer-focused business.

In addition, M&S currently yields 3.7% and trades on a price-to-earnings (P/E) ratio of 13.8, which compares favourably to both its sector on 17 and the FTSE 100 on 15.

Of course, you may be looking outside of the retail sector for an addition to your portfolio. If you are, The Motley Fool has come up with a shortlist of its best ideas called 5 Shares You Can Retire On.

It's completely free to take a look at the shortlist and I'd recommend you do so. Click here to view those 5 shares.