Behind the seasonal marketing hype, many of the deals can easily be beaten elsewhere.
Last week, NatWest pitched its "hat-trick" of summer savings. It hiked the rate on its Young Saver account from 4.42 to 5 per cent, and the top tier of interest (for those with more than £15,000) on its mini cash individual savings account (ISA) went up from 4.94 to 5 per cent. A one-year fixed-rate bond paying 5 per cent was also rolled out: the minimum investment is £5,000 and no withdrawals are permitted.
However, while these rates may seem attractive at first glance, a little bargain hunting soon reveals there are better deals elsewhere.
"The rate on the children's product has gone from fairly average to one of the better offers on the high street," says Rachel Thrussell of financial analyst Moneyfacts. "But there are still higher rates available."
Saffron Walden building society pays out 5.35 per cent on its instant access Ladybird account, while Chelsea building society's Ready Steady Save offers 5.1 per cent.
With the cash ISA, NatWest lags behind many accounts paying more than 5 per cent on any amount - not just for those with large sums to save. For example, Yorkshire building society's 30-day cash ISA notice account pays 5.25 per cent on £1, although that includes a 0.35 per cent bonus for two years.
Newcastle building society also unveiled a summer holiday offer, this one for people seeking an online home for their savings. With a minimum investment of £1,000, the NewcastleNet Bonus account pays 5.25 per cent, including a 0.5 per cent bonus for the first six months. But any withdrawal will be subject to a loss of 60 days' interest.
"We might have expected restricted withdrawals on an account like this," says Ms Thrussell. "But 60 days' loss of interest is a steep penalty - and will soon use up any interest."
Sainsbury's Bank has a summer sale on all internet loan applications of £5,000 or more, offering borrowers a rate of 6.5 per cent.
Although competitive, it is not good enough to top the "best buy" tables, where lenders such as Northern Rock and the Moneyback Bank are both paying internet rates of 5.7 per cent.
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