Summer time is when many of us get a bit lax with our finances – and it’s easy to see why.

The weather is nice outside, the kids may be off from school, and vacation or travel plans beckon. None of this puts you in the mindset of watching your bills or sticking to a budget.

But if you’re not careful, summer is also the time of year when a number of sneaky expenses can hit you from out of the blue.

Here are three sneaky summer expenses to watch out for – as well as the financial fixes that can solve these budget-busters.

Sneaky Expense #1: The Travel Surcharge

Have you ever noticed that summer time – the prime travel season – is precisely the season when the travel and tourism industry jacks up prices?

Airline tickets often cost more in the summer. Hotel prices go up, and so do rental-car fares as well. Hospitality companies sneak in higher fares because they know summer is when more people take vacations, especially families with children.

The Financial Fix: Tap Into Freebies

To deal with travel surcharges in the summer, cash in on freebies. Stop hoarding those frequently flyer program miles forever. Use them for high-priced airline tickets this summer. Ditto for rewards benefits you may have accrued that can let you nab free or discounted car rentals.

For example, my husband and I recently booked airline tickets to Florida for our family. Instead of spending our hard-earned dollars, we cashed in some frequent flyer miles we’d accrued – saving ourselves $2,250. We also have a $500 Avis coupon we’ll be using toward a car rental.

As for hotels, try ditching those high-priced properties and opt instead for free accommodations via travel sites like HomeExchange.com or LoveHomeSwap.com. You can travel anywhere, live like a local, and stay in spacious digs at no cost.

LoveHomeSwap.com says its members save about $3,500 per trip.

Sneaky Expense #2: The “Free Trial Offer” That’s Not So Free

In the summer time, many of us want to get our bodies in tip-top shape – especially if you want to slip into a bikini or spend some time in swimming trunks at the beach. Well, in order to look good, many people join a gym in the summer and they sign up for promotional or “free trial” gym memberships.

In the summer, other people love to simply curl up on a beach chair with a good book, so they take advantage of a “free trial offer” for book clubs or magazines.

A problem happens, however, when something that was supposed to be just a 30- or 60-day free trial offer later appears as a sneaky monthly bill on your credit card.

The Financial Fix: Use the Right Credit Card – or Your Calendar

Usually when you get a so-called “free trial offer” to try out a new product or service, the company still wants you to give up your credit card. If this is the case, use the right card – like a Capital One card, which will help you detect unwanted charges.

Capital One just became the first U.S. bank to start giving customers email alerts about unexpected or questionable charges – like duplicate charges, and sneaky charges for products or service that start out as free, and then change to paid offers.

The alert system is called Second Look and it flags certain recurring charges, like subscription renewals, so you can question the merchant about it or ask the bank to remove the charge.

If you don’t have a Capital One card, the next best solution is to use your calendar wisely. Go online and set up a calendar notice, as a reminder to tell you when to cancel a “free” product or service so you don’t get charged for it.

Sneaky Expense #3: Backyard Barbecues

Lots of people like to entertain in the summer, especially by having family and friends come over for a backyard barbecue. Weekends are prime time for this, and so are summer holidays like the Fourth of July.

But with those barbecues, not only do you typically have to foot the bill for food and drinks, but many people wind up spending a small fortune buying extra furniture too. Who wouldn’t like a new outdoor table, extra lawn chairs or even a fancy grill?

The Financial Fix: Consider Potlucks and Rentals

If you’re having a big backyard blowout, there’s no rule that says you have to feed a small army all by yourself. Instead of springing for the entire meal (and doing all the cooking), why not make it a potluck affair?

It just requires some brief coordination with relatives and pals to decide who’s bringing what. By having your guests each bring a dish, you can slash your food budget by up to 75%.

Also, resist the urge to buy new outdoor furniture – especially if you’re only have one or two shindigs. You can rent chairs on the cheap, or even borrow needed furniture ahead of time from a family member or friend.

By using the financial fixes mentioned above, and watching out for sneaky summer expenses, you’ll keep your budget in tact even as you have lots of summer fun.