diff --git a/src/phases/weather-effect-phase.ts b/src/phases/weather-effect-phase.ts
index 73de44389d0..b48ee342780 100644
--- a/src/phases/weather-effect-phase.ts
+++ b/src/phases/weather-effect-phase.ts
@@ -44,7 +44,7 @@ export class WeatherEffectPhase extends CommonAnimPhase {
             return;
           }
 
-          const damage = Math.ceil(pokemon.getMaxHp() / 16);
+          const damage = Utils.toDmgValue(pokemon.getMaxHp() / 16);
 
           this.scene.queueMessage(getWeatherDamageMessage(this.weather?.weatherType!, pokemon)!); // TODO: are those bangs correct?
           pokemon.damageAndUpdate(damage, HitResult.EFFECTIVE, false, false, true);
diff --git a/src/test/arena/weather_hail.test.ts b/src/test/arena/weather_hail.test.ts
index 31d20be2ded..2070e40dbcc 100644
--- a/src/test/arena/weather_hail.test.ts
+++ b/src/test/arena/weather_hail.test.ts
@@ -39,7 +39,7 @@ describe("Weather - Hail", () => {
     await game.phaseInterceptor.to("TurnEndPhase");
 
     game.scene.getField(true).forEach(pokemon => {
-      expect(pokemon.hp).toBeLessThan(pokemon.getMaxHp() - Math.floor(pokemon.getMaxHp() / 16));
+      expect(pokemon.hp).toBe(pokemon.getMaxHp() - Math.max(Math.floor(pokemon.getMaxHp() / 16), 1));
     });
   });
 
@@ -56,6 +56,20 @@ describe("Weather - Hail", () => {
     const enemyPokemon = game.scene.getEnemyPokemon()!;
 
     expect(playerPokemon.hp).toBe(playerPokemon.getMaxHp());
-    expect(enemyPokemon.hp).toBeLessThan(enemyPokemon.getMaxHp() - Math.floor(enemyPokemon.getMaxHp() / 16));
+    expect(enemyPokemon.hp).toBe(enemyPokemon.getMaxHp() - Math.max(Math.floor(enemyPokemon.getMaxHp() / 16), 1));
+  });
+
+  it("does not inflict damage to Ice type Pokemon", async () => {
+    await game.classicMode.startBattle([Species.CLOYSTER]);
+
+    game.move.select(Moves.SPLASH);
+
+    await game.phaseInterceptor.to("TurnEndPhase");
+
+    const playerPokemon = game.scene.getPlayerPokemon()!;
+    const enemyPokemon = game.scene.getEnemyPokemon()!;
+
+    expect(playerPokemon.hp).toBe(playerPokemon.getMaxHp());
+    expect(enemyPokemon.hp).toBe(enemyPokemon.getMaxHp() - Math.max(Math.floor(enemyPokemon.getMaxHp() / 16), 1));
   });
 });
diff --git a/src/test/arena/weather_sandstorm.test.ts b/src/test/arena/weather_sandstorm.test.ts
index 91188de6985..2419ca11b70 100644
--- a/src/test/arena/weather_sandstorm.test.ts
+++ b/src/test/arena/weather_sandstorm.test.ts
@@ -1,4 +1,6 @@
 import { WeatherType } from "#app/data/weather";
+import { Abilities } from "#app/enums/abilities";
+import { Stat } from "#app/enums/stat";
 import { Moves } from "#enums/moves";
 import { Species } from "#enums/species";
 import GameManager from "#test/utils/gameManager";
@@ -37,7 +39,7 @@ describe("Weather - Sandstorm", () => {
     await game.phaseInterceptor.to("TurnEndPhase");
 
     game.scene.getField(true).forEach(pokemon => {
-      expect(pokemon.hp).toBeLessThan(pokemon.getMaxHp() - Math.floor(pokemon.getMaxHp() / 16));
+      expect(pokemon.hp).toBe(pokemon.getMaxHp() - Math.max(Math.floor(pokemon.getMaxHp() / 16), 1));
     });
   });
 
@@ -53,6 +55,37 @@ describe("Weather - Sandstorm", () => {
     const enemyPokemon = game.scene.getEnemyPokemon()!;
 
     expect(playerPokemon.hp).toBe(playerPokemon.getMaxHp());
-    expect(enemyPokemon.hp).toBeLessThan(enemyPokemon.getMaxHp() - Math.floor(enemyPokemon.getMaxHp() / 16));
+    expect(enemyPokemon.hp).toBe(enemyPokemon.getMaxHp() - Math.max(Math.floor(enemyPokemon.getMaxHp() / 16), 1));
+  });
+
+  it("does not inflict damage to Rock, Ground and Steel type Pokemon", async () => {
+    game.override
+      .battleType("double")
+      .enemySpecies(Species.SANDSHREW)
+      .ability(Abilities.BALL_FETCH)
+      .enemyAbility(Abilities.BALL_FETCH);
+
+    await game.classicMode.startBattle([Species.ROCKRUFF, Species.KLINK]);
+
+    game.move.select(Moves.SPLASH, 0);
+    game.move.select(Moves.SPLASH, 1);
+
+    await game.phaseInterceptor.to("TurnEndPhase");
+
+    game.scene.getField(true).forEach(pokemon => {
+      expect(pokemon.hp).toBe(pokemon.getMaxHp());
+    });
+  });
+
+  it("increases Rock type Pokemon Sp.Def by 50%", async () => {
+    await game.classicMode.startBattle([Species.ROCKRUFF]);
+
+    const playerPokemon = game.scene.getPlayerPokemon()!;
+    const playerSpdef = playerPokemon.getStat(Stat.SPDEF);
+    expect(playerPokemon.getEffectiveStat(Stat.SPDEF)).toBe(Math.floor(playerSpdef * 1.5));
+
+    const enemyPokemon = game.scene.getEnemyPokemon()!;
+    const enemySpdef = enemyPokemon.getStat(Stat.SPDEF);
+    expect(enemyPokemon.getEffectiveStat(Stat.SPDEF)).toBe(enemySpdef);
   });
 });