diff --git a/esphome/components/climate/climate_traits.cpp b/esphome/components/climate/climate_traits.cpp
index 3af0e609a8..398e25f69e 100644
--- a/esphome/components/climate/climate_traits.cpp
+++ b/esphome/components/climate/climate_traits.cpp
@@ -8,13 +8,25 @@ namespace esphome::climate {
 static const std::vector<const char *> EMPTY_CUSTOM_MODES;  // NOLINT
 
 const std::vector<const char *> &ClimateTraits::get_supported_custom_fan_modes() const {
-  // Compat: return empty ref when pointer is null. Remove in 2026.11.0 (change return to const vector *).
-  return this->supported_custom_fan_modes_ ? *this->supported_custom_fan_modes_ : EMPTY_CUSTOM_MODES;
+  if (this->supported_custom_fan_modes_) {
+    return *this->supported_custom_fan_modes_;
+  }
+  // Compat: fall back to owned vector from deprecated setters. Remove in 2026.11.0.
+  if (!this->compat_custom_fan_modes_.empty()) {
+    return this->compat_custom_fan_modes_;
+  }
+  return EMPTY_CUSTOM_MODES;
 }
 
 const std::vector<const char *> &ClimateTraits::get_supported_custom_presets() const {
-  // Compat: return empty ref when pointer is null. Remove in 2026.11.0 (change return to const vector *).
-  return this->supported_custom_presets_ ? *this->supported_custom_presets_ : EMPTY_CUSTOM_MODES;
+  if (this->supported_custom_presets_) {
+    return *this->supported_custom_presets_;
+  }
+  // Compat: fall back to owned vector from deprecated setters. Remove in 2026.11.0.
+  if (!this->compat_custom_presets_.empty()) {
+    return this->compat_custom_presets_;
+  }
+  return EMPTY_CUSTOM_MODES;
 }
 
 int8_t ClimateTraits::get_target_temperature_accuracy_decimals() const {
diff --git a/esphome/components/climate/climate_traits.h b/esphome/components/climate/climate_traits.h
index 86ebf33c48..939bf96ed5 100644
--- a/esphome/components/climate/climate_traits.h
+++ b/esphome/components/climate/climate_traits.h
@@ -148,7 +148,8 @@ class ClimateTraits {
   bool supports_fan_mode(ClimateFanMode fan_mode) const { return this->supported_fan_modes_.count(fan_mode); }
   bool get_supports_fan_modes() const {
     return !this->supported_fan_modes_.empty() ||
-           (this->supported_custom_fan_modes_ && !this->supported_custom_fan_modes_->empty());
+           (this->supported_custom_fan_modes_ && !this->supported_custom_fan_modes_->empty()) ||
+           !this->compat_custom_fan_modes_.empty();  // Compat: remove in 2026.11.0
   }
   const ClimateFanModeMask &get_supported_fan_modes() const { return this->supported_fan_modes_; }
 
@@ -159,19 +160,21 @@ class ClimateTraits {
   // Remove before 2026.11.0
   ESPDEPRECATED("Call set_supported_custom_fan_modes() on the Climate entity instead. Removed in 2026.11.0", "2026.5.0")
   void set_supported_custom_fan_modes(std::initializer_list<const char *> modes) {
-    // NOLINT - intentional leak: pointer must survive copies of ClimateTraits
-    this->supported_custom_fan_modes_ = new std::vector<const char *>(modes);  // NOLINT
+    // Compat: store in owned vector. Copies copy the vector (same cost as before this PR).
+    this->compat_custom_fan_modes_ = modes;
   }
   // Remove before 2026.11.0
   ESPDEPRECATED("Call set_supported_custom_fan_modes() on the Climate entity instead. Removed in 2026.11.0", "2026.5.0")
   void set_supported_custom_fan_modes(const std::vector<const char *> &modes) {
-    this->supported_custom_fan_modes_ = new std::vector<const char *>(modes);  // NOLINT
+    this->compat_custom_fan_modes_ = modes;
   }
 
   // Compat: returns const ref with empty fallback. In 2026.11.0 change to return const vector *.
   const std::vector<const char *> &get_supported_custom_fan_modes() const;
   bool supports_custom_fan_mode(const char *custom_fan_mode) const {
-    return this->supported_custom_fan_modes_ && vector_contains(*this->supported_custom_fan_modes_, custom_fan_mode);
+    return (this->supported_custom_fan_modes_ &&
+            vector_contains(*this->supported_custom_fan_modes_, custom_fan_mode)) ||
+           vector_contains(this->compat_custom_fan_modes_, custom_fan_mode);  // Compat: remove in 2026.11.0
   }
   bool supports_custom_fan_mode(const std::string &custom_fan_mode) const {
     return this->supports_custom_fan_mode(custom_fan_mode.c_str());
@@ -190,18 +193,19 @@ class ClimateTraits {
   // Remove before 2026.11.0
   ESPDEPRECATED("Call set_supported_custom_presets() on the Climate entity instead. Removed in 2026.11.0", "2026.5.0")
   void set_supported_custom_presets(std::initializer_list<const char *> presets) {
-    this->supported_custom_presets_ = new std::vector<const char *>(presets);  // NOLINT
+    this->compat_custom_presets_ = presets;
   }
   // Remove before 2026.11.0
   ESPDEPRECATED("Call set_supported_custom_presets() on the Climate entity instead. Removed in 2026.11.0", "2026.5.0")
   void set_supported_custom_presets(const std::vector<const char *> &presets) {
-    this->supported_custom_presets_ = new std::vector<const char *>(presets);  // NOLINT
+    this->compat_custom_presets_ = presets;
   }
 
   // Compat: returns const ref with empty fallback. In 2026.11.0 change to return const vector *.
   const std::vector<const char *> &get_supported_custom_presets() const;
   bool supports_custom_preset(const char *custom_preset) const {
-    return this->supported_custom_presets_ && vector_contains(*this->supported_custom_presets_, custom_preset);
+    return (this->supported_custom_presets_ && vector_contains(*this->supported_custom_presets_, custom_preset)) ||
+           vector_contains(this->compat_custom_presets_, custom_preset);  // Compat: remove in 2026.11.0
   }
   bool supports_custom_preset(const std::string &custom_preset) const {
     return this->supports_custom_preset(custom_preset.c_str());
@@ -270,8 +274,11 @@ class ClimateTraits {
     return this->find_custom_fan_mode_(custom_fan_mode, strlen(custom_fan_mode));
   }
   const char *find_custom_fan_mode_(const char *custom_fan_mode, size_t len) const {
-    return this->supported_custom_fan_modes_ ? vector_find(*this->supported_custom_fan_modes_, custom_fan_mode, len)
-                                             : nullptr;
+    if (this->supported_custom_fan_modes_) {
+      return vector_find(*this->supported_custom_fan_modes_, custom_fan_mode, len);
+    }
+    // Compat: check owned vector from deprecated setters. Remove in 2026.11.0.
+    return vector_find(this->compat_custom_fan_modes_, custom_fan_mode, len);
   }
 
   /// Find and return the matching custom preset pointer from supported presets, or nullptr if not found
@@ -280,8 +287,11 @@ class ClimateTraits {
     return this->find_custom_preset_(custom_preset, strlen(custom_preset));
   }
   const char *find_custom_preset_(const char *custom_preset, size_t len) const {
-    return this->supported_custom_presets_ ? vector_find(*this->supported_custom_presets_, custom_preset, len)
-                                           : nullptr;
+    if (this->supported_custom_presets_) {
+      return vector_find(*this->supported_custom_presets_, custom_preset, len);
+    }
+    // Compat: check owned vector from deprecated setters. Remove in 2026.11.0.
+    return vector_find(this->compat_custom_presets_, custom_preset, len);
   }
 
   uint32_t feature_flags_{0};
@@ -304,6 +314,10 @@ class ClimateTraits {
    */
   const std::vector<const char *> *supported_custom_fan_modes_{nullptr};
   const std::vector<const char *> *supported_custom_presets_{nullptr};
+  // Compat: owned storage for deprecated setters. Copies copy the vector (same cost as pre-PR).
+  // Remove in 2026.11.0.
+  std::vector<const char *> compat_custom_fan_modes_;
+  std::vector<const char *> compat_custom_presets_;
 };
 
 }  // namespace esphome::climate