"You should have been here last week - the weather was glorious!"
That surely is the most annoying thing you can hear on holiday. But arriving at the wrong time of year is an easy mistake to make, particularly on a long-haul holiday. You could land in the middle of a tropical cyclone. You may find you've paid over the odds to travel in the peak season, when the 'off' season would have been just as good.
To ensure you have perfect timing, here are six tricky destinations - and some (slightly unconventional) suggestions for the best time of year to visit them.
Best time to go: May or June
Peak season in the Caribbean runs from Christmas to Easter - that's when the likes of Simon Cowell and Cliff Richard can be seen parading in their swimming trunks at five-star hotels such as Sandy Lane in Barbados. Although it's a great time to visit, hotel rates and airfares can be frighteningly expensive.
July and August are also popular months, because that is when families want to travel. However, visitors in the summer should be prepared for high humidity, frequent rainfall and even the (slight) possibility of hurricanes.
If you're not tied to school holidays, it's better to go in May or June when the weather is still fine, the beaches are empty and prices have plummeted. It's not unusual to find 40% off brochure prices at this time.
New York City
Best time to go: last weekend in November
Even if you can find a cheap flight to New York you will struggle to get a good-value hotel room at most times of year. The exception is Thanksgiving weekend when Americans traditionally go home to stay with Mom and Pop.
With no guests, hotels in the big cities drop their rates dramatically.
However, this is actually a great time to be in New York City: all the big department stores have unveiled their Christmas window displays, you can go ice skating in Central Park and the traffic stops for a colourful Thanksgiving parade through the streets of Manhattan.
For example, I found a double room at the stylish Paramount Times Square for £120 a night over Thanksgiving weekend at Hotelclub. The same room would have cost £210 a night the following weekend.
Safari in Kenya
Best time to go: November
The peak season in the safari parks of Kenya is July to September when half a million wildebeest migrate north from the Serengeti. It's also when masses of tourists turn up, particularly in the Masai Mara where temporary camps have to be set up to house the crowds.
Although the stampede is an amazing spectacle, experts recommend going instead during the 'short rains' in November. Rain falls in quick bursts, sparking spectacular electrical storms. This causes the dust to clear and green shoots to appear across the plains.
November is also the time when the wildebeest begin their long march back to the Serengeti. Lines of animals can be seen stretching for miles, without another tourist bus in sight.
Best time to go: May
Many people wrongly assume that because Mauritius lies in the southern hemisphere, the best time to go is the northern winter. Although the weather during January, February and March can be excellent, there is a risk of cyclones which can seriously mess up your visit.
July and August are also unreliable, as temperatures can be cooler than at home. The best months to visit are April, May, October and November. Of those, May is the smartest choice because it's the month when hotels roll out their best deals.
The Red Sea
Best time to go: June
The Red Sea is advertised as a year-round destination, but frankly it's too hot in August - when the temperature can top 40ºC - and it's too chilly in January and February for guaranteed sunbathing. The best times to go are the 'shoulder season' months of May, June, September and October.
In September the sea is deliciously warm, but if you want to dive or snorkel, June is the best month. A plankton bloom brings out the big fish, including whale sharks, hammerheads and huge manta rays.
Best time to go: August
There is no right or wrong time to go to South Africa. Peak season is our winter, with prices rocketing over Christmas and New Year. But there is a good argument for going to the Western Cape in August, particularly for families with school-age children.
Hotel rates are around 40% lower than in peak months, and airfares are reasonable. August is the height of the whale-watching season in Hermanus, which is a short drive from Cape Town. It's also a great time to visit Kruger National Park if you want to include a safari.
* Mark Hodson is editor of 101 Holidays
Follow Mark Hodson on Twitter: www.twitter.com/101holidays