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!
Heat Stable Vanilla Buttercream
Ingredients
- 1/2 Cup (113g) unsalted butter, room temperature
- 1/2 Cup (100g) shortening use high-ratio shortening if possible
- 3 1/2 Cups (420g) powdered sugar
- 1 Tbsp meringue powder (optional)*
- 2 tsp vanilla extract
- 2 Tbsp (30ml) whole milk or heavy whipping cream, room temperature
- 1/4 tsp salt, or to taste
Instructions
- With a hand mixer or paddle attachment on your stand mixer, cream the butter and shortening on medium-high until it’s creamy and light (almost white) in color, about 7 minutes.
- Whisk the meringue powder (if using) into the powdered sugar. Then, add the meringue/powdered sugar mixture one cup at a time, mixing on low speed and scraping down the bowl and paddle after each addition.
- Add the vanilla, milk, and salt and mix on low speed for another 1-2 minutes, until fully incorporated.
Notes
- Frost 12-15 cupcakes with a piping bag
- Fill and crumb coat a three-layer 6-inch cake or two-layer 8-inch cake. To have enough for frosting and decorating as well, double the recipe.
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!
Hi! I’m making a cake for my twin niece and nephew second birthday party in late July! The event center will be outside at a splash pad! I’m in Salt Lake City, Utah and the summers here can get up to 90°-100°. (Desert life sucks…) Will this buttercream survive extremely hot temps? I’m pretty sure the dessert table will be shaded.
Hi Shantell! Wow, that is very hot weather! As long as the dessert table is shaded and you keep the cake refrigerated until right before you head to the event, it should be totally fine for at least an hour or two. Hope that helps!
I doubled the recipe, including the meringue powder. Now the buttercream taste off. Sweeter than normal. Should I have only added 1 tbsp of meringue powder instead of 2? Do I just add a little more salt to balance the sweetness?
Hi Teresa-Ann! The doubling of the recipe should have produced the same flavor as long as all of the ingredients were doubled. If it’s sweeter than normal that would moreso point to adding too much powdered sugar. You could absolutely add more salt to balance the sweetness.
Hi there I am Rehvathi from Malaysia,I would like to know how to fix when the texture is grainy. Your help is much needed. Thank you.
Hi Rehvathi! If the texture is grainy, it typically means the powdered sugar isn’t fully dissolved. Keep mixing it on low speed for an additional 1-5 minutes. Hope that helps!
Greetings, I’m from India, where the weather is extremely hot and humid. I just wanted to ask if this butter cream would still work in humid conditions because I’m making an engagement cake for my niece, which is taking place in the midst of summer. Despite my concerns, I appreciate you sharing this recipe and can’t wait to try it.God bless you .
Hi Deepa! This recipe should work great in hot/humid weather but I would test it ahead of time just to make sure. Enjoy!
How long can this be unrefrigerated for?
Hi Stacey! It can technically be at room temperature for a few days, but if it’s on a cake in hot weather it will depend on how hot/humid and whether or not it’s in direct sunlight. It should last for several hours if it’s in the shade and the temperature is less than 85 degrees. The blog post above explains some experimenting I did with heat and humidity.
Hi I was wondering if I was to do the half butter half shortening with the mock Swiss meringue buttercream would it still be this stable?
Hi Kelly! I’ve never made mock swiss meringue buttercream (now I want to though!) so I’m not sure exactly what the results would be. It would be an experiment!
Hi, whitney nice to meet you! Living in Indonesia, which has high temperatures, has made me try lots of buttercream recipes that can withstand high temperatures. Thank you for this recipe ^-^ I have a question, if I want to use couverture chocolate, what’s the ratio between powdered sugar and couverture chocolate? Thankyou
Hi Lita! I’ve never tried adding melted chocolate to this recipe, so I’m not entirely sure. Instead, I would make this chocolate buttercream recipe with cocoa powder but sub half of the butter with high ratio shortening + add 1 Tbsp of meringue powder: https://sugarandsparrow.com/chocolate-buttercream-recipe/
The same brand of shortening you recommend is no longer available on Amazon. That brand does carry a buttercream mix that already has the meringue powder in it though. Have you tried that product, or is there a different brand of shortening you would recommend? The other brands I see on Amazon only have 50lb sizes available and are pricey. I’m a home baker, so I don’t need that much product.
Hi Laura! I have never tried that buttercream mix, my biggest concern is that it wouldn’t taste good. If that brand of high ratio shortening is sold out though there are other brands that will do just as well. Try Googling “high ratio shortening” or “cake and icing shortening” and any of the brands available should work. Some notable ones I’ve tried before are Sweetex and Alpine. Hope that helps!
I used this recipe for my cousin’s 3-tier, pearl covered wedding cake. It was an outdoor/ indoor venue in the beginning of September in Michigan (very hard to know how hot it could have been). This frosting held up beautifully and kept all the sugar pearls (many of them quite large) perfectly in place! Also, everyone LOVED how it tasted. Thank you much for an awesome recipe that took quite of a bit of anxiety out of putting together my first wedding cake for someone else!
Yay, Lillian! That makes me so happy, especially that it helped reduce your anxiety. Your first wedding cake is a HUGE deal and I’m so proud of you!
I’ve used this recipe 2x now for my Daughter’s June birthday in Wisconsin. Definitely holds up. Can’t find HRS but used Crisco and still works well.
Any suggestions on how I could get it to spread better?
Yay, Celina! So happy it worked well with Crisco! If it ends up too thick you can add an additional Tablespoon of room temperature milk to thin it out and make it more spreadable. Keep adding more room temperature milk as needed. Hope that helps!
Just wondering why you omit the meringue powder in the vegan version of this recipe? Thank you
Hi there! Simply because meringue powder is made from egg whites and isn’t vegan. Otherwise I would include it!
Thank you for this recipe! I was asked (by a friend of the family) to make my first wedding cake.
Being in SoCal during August made me nervous, but after a lot of research I went with this buttercream recipe. I made sure to test the buttercream on a practice cake. It was delicious!
I was told the wedding party loved the cake and it didn’t break a sweat! Thank you! I look forward to trying out your other recipes!
Yay, Teresa-Ann! I’m so glad this recipe helped and congratulations on making your first wedding cake! That is a huge deal and I’m so proud of you 🙂 So happy it was a hit with the guests too!
Hi! Love the attention to high-humidity requirements. Couple of questions:
Does this recipe scale well? I need to decorate over 40 cupcakes.
How many cups per dozen when piping decorations, not just smoothing some on?
Thanks!
Hi Kathy! Yes, this recipe scales really well. It makes 3 Cups, which is enough to pipe decorations on about 15 cupcakes. I’d make 2.5x the recipe to make enough for 40 cupcakes. Hope that helps!
Do you actually prepare the meringue powder, or do you just add the “dry” meringue powder to the ingredients?
Hi Sheri! I use this dry meringue powder: https://amzn.to/458wEEN hope that helps!
This is my new go to vanilla icing. I used it for my sisters wedding cake, outdoor reception-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. It wasn’t nearly as sweet as my normal American buttercream and it didn’t have a strange aftertaste like when I use regular shortening. Thank you so much for sharing, it was a lifesaver!
I’m so happy to hear that, Shauna! Thanks so much for your feedback!