Stable Vanilla Buttercream Recipe for Hot Weather

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One Summer, something happened to me that had never happened before (and thankfully hasn’t happened since): one of my cakes melted in the outdoor heat. I made a birthday cake for a dear friend’s daughter – my vegan vanilla cake with vegan vanilla buttercream. The party was outdoors and the temperature was around 85ºF (29ºC). I refrigerated the cake up until I needed to drive it to the party, thinking that would be enough to preserve it for a few hours. But about an hour after the cake was displayed, the thing started melting (along with my heart). Thankfully, these were the kind of friends who were able to laugh about it with me as it all fell apart.

In light of the melted cake, I decided to conduct some experiments to find the perfect buttercream recipe for hot weather that actually tastes good! The winning recipe can be adapted to make all kinds of flavors and has gone on to help many readers create buttercream cakes that handle the heat of outdoor events all over the world.

One Reader, Shauna, says: “This is my new go to vanilla icing! I used it for my sister’s wedding cake – an outdoor reception in July in the South. It was hot and humid and this cake remained beautiful. Not only did it hold up well, it was absolutely delicious and not nearly as sweet as normal American buttercream. A lifesaver!”

How Hot is Too Hot for a Buttercream Cake? 

Whether you’re using American buttercream, Swiss Meringue buttercream, or another butter-based frosting, here’s what happens to buttercream cakes at different temperatures:

• Above 75ºF: the buttercream begins to soften.
• Above 82ºF: the buttercream starts to break down and buttercream details begin to droop.
• Above 90ºF: the buttercream starts to melt completely as it approaches the actual melting point of butter.  

Keep in mind that the melting temperature for vegan butter is even lower, so these temperatures shift lower for a vegan buttercream frosted cake (like the melted one pictured above).

Ingredients that Stabilize Buttercream for Hot Weather

There are a few key ingredients that make the winning buttercream more heat stable:

• Shortening. Replacing at least half of the butter in any American buttercream recipe with shortening will make it incredibly heat resistant. If you have access to it, opt for high-ratio shortening for the smoothest flavor and most heat resistance. If you can’t easily find it, Crisco will get the job done. 
• Powdered Sugar. In an American buttercream (which is the base of the recipe pictured throughout this post), powdered sugar helps thicken the frosting and create an outer crust for the buttercream that helps keep its shape. I don’t use as much powdered sugar as the average American buttercream recipe which keeps the sweetness level minimal. 
• Meringue Powder. This is essentially a mixture of powdered egg whites and other stabilizing ingredients like cream of tartar and gum arabic. Adding a little meringue powder helps absorb moisture and create more structure that helps frosting hold its shape (especially piped details) in warm weather.

Hot Weather Buttercream Recipe Tests

To come up with the winning hot weather buttercream recipe, I conducted an experiment to test out different ingredients for stabilizing. I created four cakes and decorated each with a different frosting using my favorite vanilla buttercream recipe as a base. I tested: 

• All butter (aka the recipe as-is)
• Half butter and half shortening
• All shortening in place of the butter in the recipe
• Half vegan butter and half shortening (with coconut milk as the liquid)

After refrigerating each cake until the frosting was firm, I placed them in the direct sun on an 88ºF day. Here’s a video of what happened:

I had the cakes in the sun for 2 hours, but none of them completely melted, which was kind of disappointing because I wanted things to be more dramatic. So in the end, I broke out the hair dryer to see what would happen with more heat applied. After I cranked up the heat on these cakes to the melting point of butter:

• The all-butter buttercream cake: melted into soup. No surprises there. 
• The half butter and half shortening cake: started to settle a bit (but nothing crazy). This one had the best flavor for a heat stable buttercream. 
• The all-shortening cake: had relatively no change, but the flavor wasn’t as good as it was with half butter. 
• The half vegan butter and half shortening cake: got a huge air bubble in the frosting and started to melt.

With taste and stability in mind, if you’re up against heat above 82ºF, I’d recommend using at least half butter and half shortening. If you need even more structure, consider adding some meringue powder (instructions in the recipe below) or using all shortening.

Hot Weather Buttercream FAQ

• Why does high-ratio shortening work better than Crisco? High-ratio shortening (also known as icing shortening) has a high ratio of fat with added emulsifiers and zero water content. This helps the frosting hold more sugar and liquid, makes it more temperature resistant, and the resulting buttercream has a much smoother (not greasy or gritty!) texture. 
• What if I can’t find high-ratio shortening anywhere? It’s usually available on Amazon, but if you’re in a pinch, a regular vegetable shortening like Crisco will work just fine. 
• Should I add meringue powder? If you’ve got a cake with intricate piping and are concerned about hot weather, I would add about 1 tablespoon of meringue powder per batch of buttercream for extra stability. 
• Are there other ways to make heat stable buttercream? Adding shortening to an American buttercream recipe is the easiest way to make a heat stable buttercream, but I’ve also heard that Italian meringue and ermine frosting are both very heat stable.

Best Practices for Cakes at Outdoor Events 

Now that you know more about how to make your buttercream cake more heat stable, here are some best practices for ensuring that frosting stays put at an outdoor event:

• Refrigerate the cake until the moment you need to transport it to your event. 
• If possible, refrigerate the cake until you’re ready to display it at the event. This way, it should take at least an hour for the cake to come to room temperature while on display (the ideal temperature for eating the cake)! 
• Place the cake in the shade, not in the direct sun.
• Read up on the weather and outdoor temperature beforehand, so you know how much extra stability you need in your frosting.

I hope this covers everything you need to know about making buttercream cakes heat stable! If you make this buttercream, let me know how it went in the comments below (don’t forget to rate the recipe!) and feel free to tag @sugarandsparrowco on Instagram if you post a photo. Happy hot weather caking!

Did you try this recipe? I want to know that you think! Let me know in the comments below or feel free to tag @sugarandsparrowco on Instagram and show me. I love to see what you create! And if you have a go-to recipe for heat stable buttercream or technique that you swear by, let us all know in the comments. We’re all in this together!