With temperatures across Britain once again plummeting this week, a rotten 2012 looks set to be followed by an equally problematic 2013 for farmers and growers - with inevitable knock-on effects on prices in the supermarkets.

The bad weather is making life difficult for producers in all sectors, but fresh produce has experienced particularly acute problems with supply in the UK and abroad, leading to rising wholesale as well as retail prices in many categories.

The potato’s problems are well-documented. As The Grocer reported earlier this month average retail prices on fresh potato SKUs in the mults are now about 20% higher than they were a year ago.

But potatoes are far from the only crop to have been hammered by bad weather in 2012 and 2013. In the fruit aisle, for example, pear prices have shot up thanks to a double whammy of poor production in northern Europe last year followed by a bad season in Argentina, the world’s largest pear exporter. The average price of a pear SKU in the mults has increased by 12% over the past year - from an average of £1.72 to £1.95 - while loose Conference pears have risen by a whopping 47%, from £1.70/kg to £2.50/kg.

Cold weather hits fruit & veg wholesale prices

If you thought the weather was taking its toll on retail fruit & veg prices, check out the situation in wholesale: seven of the 10 items in our tracker increased in price.

Iceberg lettuce is a rare exception. Cool weather in Spain resulted in reduced output and pushed up prices 14.7% over the past month, yet availability is better than this time last year, leading prices to fall 21.1% year-on-year.

Wholesale prices have also fallen for bananas, thanks to good production runs preventing the usual seasonal spike. As a result, they are 17.2% cheaper year-on-year and down 5.4% month-on-month.

Prices for salad tomatoes in the UK have also bucked the seasonal trend, with prices falling in January thanks to good supply from Spain. More recently cooler weather in Spain has hindered harvests, and supply from the Netherlands is limited, causing prices to rise 34.5% month-on-month.

Another crop badly impacted is peppers: wholesale prices have risen sharply in recent weeks as Spanish supply has come to an end, and peppers from the Netherlands are not yet ready because of the hostile conditions in 2012 and 2013.

Higher wholesale prices have translated into higher retail prices for several key pepper SKUs - albeit to varying degrees in different retailers.

In Tesco, a pack of three mixed peppers has gone up by 35p, from £1.65 to £2, over the past 12 months, and a 700g budget pack has increased by 60p, from £1.50 to £2.10. The equivalent lines have also grown more expensive in Asda, with a three-pack up from £1.65 to £1.80, and a 700g budget pack up 27p, from £1.50 to £1.77.

By contrast, Sainsbury’s and Morrisons have been cutting pepper prices, reducing their standard three-packs from £1.80 to £1.65. Budget peppers are also down in both retailers, with the Sainsbury’s 600g pack cut from £1.75 to £1.51, and the 500g pack in Morrisons down from £1.80 to £1.50.

Despite some multipacks going up, the price of a single, loose pepper has stayed largely stable at 80p across all mults over the past year.

It’s the opposite story in carrots and onions, both of which have experienced significant weather-related inflation at wholesale level over the past year. Here, prices for many multipack SKUs have remained stable or even decreased, but prices for loose produce have crept up. One kilogram of loose carrots now costs 90p in the mults, up by 14% from an average of 79p a year ago, and 1kg of loose brown onions now costs 92p on average, up by 21% from 76p this time last year.