diff --git a/esphome/components/light/light_call.cpp b/esphome/components/light/light_call.cpp
index 6945d37ded..d979b13368 100644
--- a/esphome/components/light/light_call.cpp
+++ b/esphome/components/light/light_call.cpp
@@ -8,26 +8,23 @@ namespace light {
 static const char *const TAG = "light";
 
 static const char *color_mode_to_human(ColorMode color_mode) {
-  switch (color_mode) {
-    case ColorMode::UNKNOWN:
-      return "Unknown";
-    case ColorMode::WHITE:
-      return "White";
-    case ColorMode::COLOR_TEMPERATURE:
-      return "Color temperature";
-    case ColorMode::COLD_WARM_WHITE:
-      return "Cold/warm white";
-    case ColorMode::RGB:
-      return "RGB";
-    case ColorMode::RGB_WHITE:
-      return "RGBW";
-    case ColorMode::RGB_COLD_WARM_WHITE:
-      return "RGB + cold/warm white";
-    case ColorMode::RGB_COLOR_TEMPERATURE:
-      return "RGB + color temperature";
-    default:
-      return "";
-  }
+  if (color_mode == ColorMode::UNKNOWN)
+    return "Unknown";
+  if (color_mode == ColorMode::WHITE)
+    return "White";
+  if (color_mode == ColorMode::COLOR_TEMPERATURE)
+    return "Color temperature";
+  if (color_mode == ColorMode::COLD_WARM_WHITE)
+    return "Cold/warm white";
+  if (color_mode == ColorMode::RGB)
+    return "RGB";
+  if (color_mode == ColorMode::RGB_WHITE)
+    return "RGBW";
+  if (color_mode == ColorMode::RGB_COLD_WARM_WHITE)
+    return "RGB + cold/warm white";
+  if (color_mode == ColorMode::RGB_COLOR_TEMPERATURE)
+    return "RGB + color temperature";
+  return "";
 }
 
 void LightCall::perform() {
diff --git a/esphome/components/ota/ota_component.cpp b/esphome/components/ota/ota_component.cpp
index 71f8101704..ac72befb9e 100644
--- a/esphome/components/ota/ota_component.cpp
+++ b/esphome/components/ota/ota_component.cpp
@@ -178,28 +178,29 @@ void OTAComponent::handle_() {
 #endif
 
   if (!Update.begin(ota_size, U_FLASH)) {
+    uint8_t error = Update.getError();
     StreamString ss;
     Update.printError(ss);
 #ifdef ARDUINO_ARCH_ESP8266
-    if (ss.indexOf("Invalid bootstrapping") != -1) {
+    if (error == UPDATE_ERROR_BOOTSTRAP) {
       error_code = OTA_RESPONSE_ERROR_INVALID_BOOTSTRAPPING;
       goto error;
     }
-    if (ss.indexOf("new Flash config wrong") != -1 || ss.indexOf("new Flash config wsong") != -1) {
+    if (error == UPDATE_ERROR_NEW_FLASH_CONFIG) {
       error_code = OTA_RESPONSE_ERROR_WRONG_NEW_FLASH_CONFIG;
       goto error;
     }
-    if (ss.indexOf("Flash config wrong real") != -1 || ss.indexOf("Flash config wsong real") != -1) {
+    if (error == UPDATE_ERROR_FLASH_CONFIG) {
       error_code = OTA_RESPONSE_ERROR_WRONG_CURRENT_FLASH_CONFIG;
       goto error;
     }
-    if (ss.indexOf("Not Enough Space") != -1) {
+    if (error == UPDATE_ERROR_SPACE) {
       error_code = OTA_RESPONSE_ERROR_ESP8266_NOT_ENOUGH_SPACE;
       goto error;
     }
 #endif
 #ifdef ARDUINO_ARCH_ESP32
-    if (ss.indexOf("Bad Size Given") != -1) {
+    if (error == UPDATE_ERROR_SIZE) {
       error_code = OTA_RESPONSE_ERROR_ESP32_NOT_ENOUGH_SPACE;
       goto error;
     }
diff --git a/esphome/components/sntp/sntp_component.cpp b/esphome/components/sntp/sntp_component.cpp
index ff176b1d4e..895c775b19 100644
--- a/esphome/components/sntp/sntp_component.cpp
+++ b/esphome/components/sntp/sntp_component.cpp
@@ -56,9 +56,8 @@ void SNTPComponent::loop() {
   if (!time.is_valid())
     return;
 
-  char buf[128];
-  time.strftime(buf, sizeof(buf), "%c");
-  ESP_LOGD(TAG, "Synchronized time: %s", buf);
+  ESP_LOGD(TAG, "Synchronized time: %d-%d-%d %d:%d:%d", time.year, time.month, time.day_of_month, time.hour,
+           time.minute, time.second);
   this->time_sync_callback_.call();
   this->has_time_ = true;
 }
diff --git a/esphome/components/time/real_time_clock.cpp b/esphome/components/time/real_time_clock.cpp
index c2a93b5191..27a2d84da6 100644
--- a/esphome/components/time/real_time_clock.cpp
+++ b/esphome/components/time/real_time_clock.cpp
@@ -35,9 +35,8 @@ void RealTimeClock::synchronize_epoch_(uint32_t epoch) {
   }
 
   auto time = this->now();
-  char buf[128];
-  time.strftime(buf, sizeof(buf), "%c");
-  ESP_LOGD(TAG, "Synchronized time: %s", buf);
+  ESP_LOGD(TAG, "Synchronized time: %d-%d-%d %d:%d:%d", time.year, time.month, time.day_of_month, time.hour,
+           time.minute, time.second);
 
   this->time_sync_callback_.call();
 }
diff --git a/esphome/components/wifi/wifi_component_esp8266.cpp b/esphome/components/wifi/wifi_component_esp8266.cpp
index ab68f421a8..ad1a64d1f4 100644
--- a/esphome/components/wifi/wifi_component_esp8266.cpp
+++ b/esphome/components/wifi/wifi_component_esp8266.cpp
@@ -366,65 +366,75 @@ const char *get_op_mode_str(uint8_t mode) {
       return "UNKNOWN";
   }
 }
+// Note that this method returns PROGMEM strings, so use LOG_STR_ARG() to access them.
 const char *get_disconnect_reason_str(uint8_t reason) {
+  /* If this were one big switch statement, GCC would generate a lookup table for it. However, the values of the
+   * REASON_* constants aren't continuous, and GCC will fill in the gap with the default value -- wasting 4 bytes of RAM
+   * per entry. As there's ~175 default entries, this wastes 700 bytes of RAM.
+   */
+  if (reason <= REASON_CIPHER_SUITE_REJECTED) {  // This must be the last constant with a value <200
+    switch (reason) {
+      case REASON_AUTH_EXPIRE:
+        return LOG_STR("Auth Expired");
+      case REASON_AUTH_LEAVE:
+        return LOG_STR("Auth Leave");
+      case REASON_ASSOC_EXPIRE:
+        return LOG_STR("Association Expired");
+      case REASON_ASSOC_TOOMANY:
+        return LOG_STR("Too Many Associations");
+      case REASON_NOT_AUTHED:
+        return LOG_STR("Not Authenticated");
+      case REASON_NOT_ASSOCED:
+        return LOG_STR("Not Associated");
+      case REASON_ASSOC_LEAVE:
+        return LOG_STR("Association Leave");
+      case REASON_ASSOC_NOT_AUTHED:
+        return LOG_STR("Association not Authenticated");
+      case REASON_DISASSOC_PWRCAP_BAD:
+        return LOG_STR("Disassociate Power Cap Bad");
+      case REASON_DISASSOC_SUPCHAN_BAD:
+        return LOG_STR("Disassociate Supported Channel Bad");
+      case REASON_IE_INVALID:
+        return LOG_STR("IE Invalid");
+      case REASON_MIC_FAILURE:
+        return LOG_STR("Mic Failure");
+      case REASON_4WAY_HANDSHAKE_TIMEOUT:
+        return LOG_STR("4-Way Handshake Timeout");
+      case REASON_GROUP_KEY_UPDATE_TIMEOUT:
+        return LOG_STR("Group Key Update Timeout");
+      case REASON_IE_IN_4WAY_DIFFERS:
+        return LOG_STR("IE In 4-Way Handshake Differs");
+      case REASON_GROUP_CIPHER_INVALID:
+        return LOG_STR("Group Cipher Invalid");
+      case REASON_PAIRWISE_CIPHER_INVALID:
+        return LOG_STR("Pairwise Cipher Invalid");
+      case REASON_AKMP_INVALID:
+        return LOG_STR("AKMP Invalid");
+      case REASON_UNSUPP_RSN_IE_VERSION:
+        return LOG_STR("Unsupported RSN IE version");
+      case REASON_INVALID_RSN_IE_CAP:
+        return LOG_STR("Invalid RSN IE Cap");
+      case REASON_802_1X_AUTH_FAILED:
+        return LOG_STR("802.1x Authentication Failed");
+      case REASON_CIPHER_SUITE_REJECTED:
+        return LOG_STR("Cipher Suite Rejected");
+    }
+  }
+
   switch (reason) {
-    case REASON_AUTH_EXPIRE:
-      return "Auth Expired";
-    case REASON_AUTH_LEAVE:
-      return "Auth Leave";
-    case REASON_ASSOC_EXPIRE:
-      return "Association Expired";
-    case REASON_ASSOC_TOOMANY:
-      return "Too Many Associations";
-    case REASON_NOT_AUTHED:
-      return "Not Authenticated";
-    case REASON_NOT_ASSOCED:
-      return "Not Associated";
-    case REASON_ASSOC_LEAVE:
-      return "Association Leave";
-    case REASON_ASSOC_NOT_AUTHED:
-      return "Association not Authenticated";
-    case REASON_DISASSOC_PWRCAP_BAD:
-      return "Disassociate Power Cap Bad";
-    case REASON_DISASSOC_SUPCHAN_BAD:
-      return "Disassociate Supported Channel Bad";
-    case REASON_IE_INVALID:
-      return "IE Invalid";
-    case REASON_MIC_FAILURE:
-      return "Mic Failure";
-    case REASON_4WAY_HANDSHAKE_TIMEOUT:
-      return "4-Way Handshake Timeout";
-    case REASON_GROUP_KEY_UPDATE_TIMEOUT:
-      return "Group Key Update Timeout";
-    case REASON_IE_IN_4WAY_DIFFERS:
-      return "IE In 4-Way Handshake Differs";
-    case REASON_GROUP_CIPHER_INVALID:
-      return "Group Cipher Invalid";
-    case REASON_PAIRWISE_CIPHER_INVALID:
-      return "Pairwise Cipher Invalid";
-    case REASON_AKMP_INVALID:
-      return "AKMP Invalid";
-    case REASON_UNSUPP_RSN_IE_VERSION:
-      return "Unsupported RSN IE version";
-    case REASON_INVALID_RSN_IE_CAP:
-      return "Invalid RSN IE Cap";
-    case REASON_802_1X_AUTH_FAILED:
-      return "802.1x Authentication Failed";
-    case REASON_CIPHER_SUITE_REJECTED:
-      return "Cipher Suite Rejected";
     case REASON_BEACON_TIMEOUT:
-      return "Beacon Timeout";
+      return LOG_STR("Beacon Timeout");
     case REASON_NO_AP_FOUND:
-      return "AP Not Found";
+      return LOG_STR("AP Not Found");
     case REASON_AUTH_FAIL:
-      return "Authentication Failed";
+      return LOG_STR("Authentication Failed");
     case REASON_ASSOC_FAIL:
-      return "Association Failed";
+      return LOG_STR("Association Failed");
     case REASON_HANDSHAKE_TIMEOUT:
-      return "Handshake Failed";
+      return LOG_STR("Handshake Failed");
     case REASON_UNSPECIFIED:
     default:
-      return "Unspecified";
+      return LOG_STR("Unspecified");
   }
 }
 
@@ -448,7 +458,7 @@ void WiFiComponent::wifi_event_callback(System_Event_t *event) {
         ESP_LOGW(TAG, "Event: Disconnected ssid='%s' reason='Probe Request Unsuccessful'", buf);
       } else {
         ESP_LOGW(TAG, "Event: Disconnected ssid='%s' bssid=" LOG_SECRET("%s") " reason='%s'", buf,
-                 format_mac_addr(it.bssid).c_str(), get_disconnect_reason_str(it.reason));
+                 format_mac_addr(it.bssid).c_str(), LOG_STR_ARG(get_disconnect_reason_str(it.reason)));
       }
       break;
     }
diff --git a/esphome/core/log.h b/esphome/core/log.h
index 0eec28101f..fbaaf14408 100644
--- a/esphome/core/log.h
+++ b/esphome/core/log.h
@@ -7,6 +7,7 @@
 #include "WString.h"
 #endif
 
+#include "esphome/core/macros.h"
 // avoid esp-idf redefining our macros
 #include "esphome/core/esphal.h"
 
@@ -162,4 +163,28 @@ int esp_idf_log_vprintf_(const char *format, va_list args);  // NOLINT
 #define ONOFF(b) ((b) ? "ON" : "OFF")
 #define TRUEFALSE(b) ((b) ? "TRUE" : "FALSE")
 
+#ifdef USE_STORE_LOG_STR_IN_FLASH
+#define LOG_STR(s) PSTR(s)
+
+// From Arduino 2.5 onwards, we can pass a PSTR() to printf(). For previous versions, emulate support
+// by copying the message to a local buffer first. String length is limited to 63 characters.
+// https://github.com/esp8266/Arduino/commit/6280e98b0360f85fdac2b8f10707fffb4f6e6e31
+#include <core_version.h>
+#if defined(ARDUINO_ARCH_ESP8266) && ARDUINO_VERSION_CODE < VERSION_CODE(2, 5, 0)
+#define LOG_STR_ARG(s) \
+  ({ \
+    char __buf[64]; \
+    __buf[63] = '\0'; \
+    strncpy_P(__buf, s, 63); \
+    __buf; \
+  })
+#else
+#define LOG_STR_ARG(s) (s)
+#endif
+
+#else
+#define LOG_STR(s) (s)
+#define LOG_STR_ARG(s) (s)
+#endif
+
 }  // namespace esphome