Quick answer: yes, blackout curtains can help keep a room cooler in summer — especially when they block direct sunlight during the hottest parts of the day.

But blackout curtains are not magic air conditioning. Their cooling effect depends on the fabric, lining, color, window direction, curtain size, and how well they cover the window. For the best result, choose curtains that block light, reduce heat from sunny windows, and fit wide enough to limit gaps around the frame.

If your bedroom, living room, nursery, or home office gets too hot in summer, the right window treatment can make the space feel darker, calmer, and more comfortable.

Why Sunny Rooms Get Hot in Summer

If a room heats up quickly during the day, your windows are often part of the problem.

When sunlight enters through glass, it warms floors, furniture, walls, and bedding. That trapped warmth can make the room feel hotter even after the sun moves away. This is especially common in rooms with:

• South-facing or west-facing windows
• Large windows or sliding glass doors
• Thin curtains or sheer-only window treatments
• Dark flooring or furniture near the window
• Gaps around curtains that let sunlight leak in
• Bedrooms that receive afternoon sun

This is why closing curtains during peak sunlight hours can help. The goal is simple: stop as much direct sunlight as possible before it enters the room.

How Blackout Curtains Help Keep a Room Cooler

Blackout curtains are designed to block light. Because sunlight is one of the biggest reasons a room heats up, blocking it can also help reduce the warm, sun-baked feeling inside the room.

They help in three main ways.

1. They block direct sunlight

The biggest benefit of blackout curtains is light control. When less sunlight enters the room, less heat is absorbed by floors, walls, and furniture.

This is especially useful for:

• Bedrooms that get early morning sun
• Living rooms with large sunny windows
• Nurseries that need a darker nap environment
• Home offices with glare on screens
• Apartments with limited control over window direction

2. They create a barrier between the window and the room

Blackout curtains add a fabric layer between the hot window area and the rest of the room. Heavier or lined curtains can help slow down the transfer of heat from the glass into the room.

This does not mean the room will instantly become cold, but it can help reduce the intensity of heat coming from sunny windows.

3. They make the room feel darker and more restful

A cooler room is not only about temperature. Bright sunlight can make a bedroom or living room feel hotter and less relaxing. Blackout curtains create a darker, calmer atmosphere, which can make the room feel more comfortable during summer afternoons.

Are Blackout Curtains the Same as 100% Total Blackout Curtains?

Not exactly.

Blackout curtains are designed to reduce light and improve privacy. They work well for everyday light control in bedrooms, living rooms, and home offices.

100% total blackout curtains are designed for stronger light blocking. They are better for rooms where darkness matters more, such as bedrooms, nurseries, west-facing rooms, and spaces where sunlight is intense.

Here is the simple difference:

If you want a darker and more comfortable room in summer, start with blackout curtains.
If you want stronger darkness and better coverage for sleep or intense sunlight, choose 100% total blackout curtains.

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Best Deconovo Picks for Hot, Sunny Rooms

If you are choosing curtains for summer comfort, do not only look at color. Look at light-blocking performance, fabric type, coverage, and whether the curtain fits your room’s needs.

Here are three Deconovo picks to consider.

1. Solene Custom Linen Texture 100% Total Blackout Curtains

Best for: sunny bedrooms, west-facing rooms, nurseries, and stronger light blocking

If your main goal is to block harsh summer sunlight, Solene is the strongest starting point. Its 100% total blackout function makes it a good fit for rooms that need deeper darkness during the day.

Solene also has a soft linen-textured look, so it works well for customers who want both function and a clean, elevated home style.

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2. Olivia Custom Linen Blackout Curtains

Best for: everyday bedroom and living room light control

Olivia is a strong everyday blackout curtain option for customers who want comfort, privacy, and a soft linen look. It works well in bedrooms, living rooms, and spaces where users want a balance of function and style.

If your room feels too bright in summer but you still want a versatile design that fits different decor styles, Olivia is a good option to consider.

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3. Charlotte Custom Linen and Cotton Blend Blackout Curtains

Best for: a refined custom curtain look with blackout comfort

Charlotte is a good choice for customers who want their curtains to feel more polished and custom. Its linen and cotton blend style makes it suitable for bedrooms and living rooms where both appearance and function matter.

If you want a more finished look for a sunny room, Charlotte can help create a softer, more designed space while still improving light control.

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Why Your Room May Still Feel Hot with Blackout Curtains

If you already have blackout curtains but your room still feels hot, the issue may not be the idea of blackout curtains. It may be the setup.

Here are the most common reasons.

1. The curtains are too narrow

If the curtain panels barely cover the window, sunlight can leak from the sides. Even small light gaps can make a room warmer and brighter.

Fix: Choose panels that extend several inches beyond the window frame on both sides.

2. The curtain rod is installed too low

When the rod sits directly above the window frame, sunlight can leak from the top.

Fix: Mount the rod higher to cover more wall space above the window.

3. The curtains are too short

Short curtains may leave sunlight and warm air movement near the bottom of the window.

Fix: For bedrooms and living rooms, consider floor-length curtains for better coverage and a more finished look.

4. The fabric blocks light but lacks thermal lining

Some blackout curtains are mainly designed for darkness, not insulation. If your room gets strong afternoon sun, you may need a heavier fabric or thermal lining.

Fix: Choose blackout curtains with insulating features or consider thermal curtains for hot rooms.

5. The curtains are open during peak sun hours

Blackout curtains work best when they are closed before the room heats up. If you close them after the sun has already warmed the room, the effect will be weaker.

Fix: Close curtains before direct sunlight hits the window, especially in the afternoon.

How to Choose Curtains for a Hot Room

If your goal is to keep a room cooler in summer, do not choose curtains based only on color or style. Focus on fit, fabric, function, and room direction.

Choose blackout or thermal function

Look for curtains designed for light blocking, thermal comfort, or total blackout. These functions are more useful for hot rooms than lightweight decorative panels.

Pick the right size

A better fit creates better coverage. For hot, sunny rooms, curtains should cover the full window area and reduce side gaps.

If your windows are large, wide, or unusual in size, custom curtains can help create a cleaner and more effective fit.

Helpful next step:
Use the Deconovo Measurement Tool

Consider lighter backings or neutral colors

Dark curtains can block light well, but they may also absorb heat if the sun hits them directly. For rooms that receive strong sunlight, curtains with a lighter backing or thermal lining can be more comfortable.

Are Blackout Curtains Enough for Summer Heat?

Blackout curtains can help, but they work best as part of a full room comfort strategy.

For better summer comfort, try these steps:

1. Close curtains before direct sunlight hits the window.

2. Use wider panels to reduce side light gaps.

3. Choose thermal or lined blackout curtains for sunny rooms.

4. Keep interior doors open when airflow is needed.

5. Use fans or air conditioning more efficiently with curtains closed.

6. Add shades or blinds if you need flexible daytime light control.

7. Choose breathable bedding in bedrooms that feel warm at night.

Blackout curtains help manage sunlight. Thermal curtains help manage temperature comfort. Shades and blinds offer more flexible control throughout the day.

For many homes, the best solution is not one product. It is the right window treatment for the room.

Explore more options:
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Common Mistakes When Using Blackout Curtains in Summer

Mistake 1: Buying panels that are the exact window width

This often creates side gaps. For better coverage, curtains should be wider than the window.

Mistake 2: Hanging the rod too close to the frame

A higher and wider rod placement helps block more light and makes the window look larger.

Mistake 3: Choosing style before function

For hot rooms, function matters first. Look for blackout, thermal, or total blackout features before choosing color and texture.

Mistake 4: Keeping curtains open during the hottest hours

If you wait until the room is already hot, curtains cannot remove the heat that has already built up.

Mistake 5: Ignoring window direction

West-facing rooms often get strong afternoon sun. These rooms may need stronger light and heat control than north-facing rooms.

Final Answer: Do Blackout Curtains Keep Rooms Cooler?

Yes, blackout curtains can help keep a room cooler in summer by blocking direct sunlight and reducing the heat that enters through windows. They work especially well in bedrooms, nurseries, home offices, and sunny living rooms.

However, the best results depend on choosing the right curtain type and installing it correctly. For hot rooms, look for blackout or thermal curtains, choose full window coverage, reduce side gaps, and close the curtains before peak sunlight.

If your current curtains still let in light or heat, it may be time to upgrade to a better-fitting solution.

Ready to make your room cooler and more comfortable?

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FAQ

Do blackout curtains really keep heat out?

Blackout curtains can help reduce heat from direct sunlight by blocking light before it enters the room. They are most effective when they fully cover the window and are closed during peak sunlight hours.

Are 100% total blackout curtains better for summer?

100% total blackout curtains are better if your room gets strong sunlight or you need deeper darkness. They are especially useful for bedrooms, nurseries, west-facing rooms, and light sleepers.

What is the difference between blackout and total blackout curtains?

Blackout curtains reduce light and improve privacy. Total blackout curtains are designed for stronger light blocking and are better for rooms where maximum darkness is important.

What color curtains are best for keeping a room cool?

Lighter colors or curtains with lighter backings may be better for sunny rooms because they are less likely to absorb heat than dark fabrics. However, fabric construction, lining, and coverage matter more than color alone.

Should blackout curtains touch the floor?

Floor-length curtains often provide better coverage and a more finished look, especially in bedrooms and living rooms. They can also help reduce light gaps near the bottom of the window.

Can blackout curtains replace air conditioning?

No. Blackout curtains can help reduce sunlight and improve comfort, but they do not replace air conditioning or proper insulation. They work best as part of a broader summer cooling strategy.