diff --git a/routes/weather.ts b/routes/weather.ts
index aa1f7e1..2dbf7f6 100644
--- a/routes/weather.ts
+++ b/routes/weather.ts
@@ -18,6 +18,12 @@ const filters = {
 	timezone: /^()()()()()()([+-])(\d{2})(\d{2})/
 };
 
+// Enum of available watering scale adjustment methods.
+const ADJUSTMENT_METHOD = {
+	ZIMMERMAN: 1,
+	RAIN_DELAY: 2
+};
+
 /**
  * Resolves a location description to geographic coordinates.
  * @param location A partial zip/city/country or a coordinate pair.
@@ -110,56 +116,49 @@ function getTimeData( coordinates: GeoCoordinates ): TimeData {
 }
 
 /**
- * Calculates how much watering should be scaled based on weather and adjustment options.
- * @param adjustmentMethod The method to use to calculate the watering percentage. The only supported method is 1, which
- * corresponds to the Zimmerman method. If an invalid adjustmentMethod is used, this method will return -1.
+ * Calculates how much watering should be scaled based on weather and adjustment options using the Zimmerman method.
  * @param adjustmentOptions Options to tweak the calculation, or undefined/null if no custom values are to be used.
  * @param wateringData The weather to use to calculate watering percentage.
- * @return The percentage that watering should be scaled by, or -1 if an invalid adjustmentMethod was provided.
+ * @return The percentage that watering should be scaled by.
  */
-function calculateWeatherScale( adjustmentMethod: number, adjustmentOptions: AdjustmentOptions, wateringData: WateringData ): number {
+function calculateZimmermanWateringScale( adjustmentOptions: AdjustmentOptions, wateringData: WateringData ): number {
 
-	// Zimmerman method
-	if ( adjustmentMethod === 1 ) {
-		let humidityBase = 30, tempBase = 70, precipBase = 0;
+	let humidityBase = 30, tempBase = 70, precipBase = 0;
 
-		// Check to make sure valid data exists for all factors
-		if ( !validateValues( [ "temp", "humidity", "precip" ], wateringData ) ) {
-			return 100;
-		}
-
-		// Get baseline conditions for 100% water level, if provided
-		if ( adjustmentOptions ) {
-			humidityBase = adjustmentOptions.hasOwnProperty( "bh" ) ? adjustmentOptions.bh : humidityBase;
-			tempBase = adjustmentOptions.hasOwnProperty( "bt" ) ? adjustmentOptions.bt : tempBase;
-			precipBase = adjustmentOptions.hasOwnProperty( "br" ) ? adjustmentOptions.br : precipBase;
-		}
-
-		let temp = wateringData.temp,
-			humidityFactor = ( humidityBase - wateringData.humidity ),
-			tempFactor = ( ( temp - tempBase ) * 4 ),
-			precipFactor = ( ( precipBase - wateringData.precip ) * 200 );
-
-		// Apply adjustment options, if provided, by multiplying the percentage against the factor
-		if ( adjustmentOptions ) {
-			if ( adjustmentOptions.hasOwnProperty( "h" ) ) {
-				humidityFactor = humidityFactor * ( adjustmentOptions.h / 100 );
-			}
-
-			if ( adjustmentOptions.hasOwnProperty( "t" ) ) {
-				tempFactor = tempFactor * ( adjustmentOptions.t / 100 );
-			}
-
-			if ( adjustmentOptions.hasOwnProperty( "r" ) ) {
-				precipFactor = precipFactor * ( adjustmentOptions.r / 100 );
-			}
-		}
-
-		// Apply all of the weather modifying factors and clamp the result between 0 and 200%.
-		return Math.floor( Math.min( Math.max( 0, 100 + humidityFactor + tempFactor + precipFactor ), 200 ) );
+	// Check to make sure valid data exists for all factors
+	if ( !validateValues( [ "temp", "humidity", "precip" ], wateringData ) ) {
+		return 100;
 	}
 
-	return -1;
+	// Get baseline conditions for 100% water level, if provided
+	if ( adjustmentOptions ) {
+		humidityBase = adjustmentOptions.hasOwnProperty( "bh" ) ? adjustmentOptions.bh : humidityBase;
+		tempBase = adjustmentOptions.hasOwnProperty( "bt" ) ? adjustmentOptions.bt : tempBase;
+		precipBase = adjustmentOptions.hasOwnProperty( "br" ) ? adjustmentOptions.br : precipBase;
+	}
+
+	let temp = wateringData.temp,
+		humidityFactor = ( humidityBase - wateringData.humidity ),
+		tempFactor = ( ( temp - tempBase ) * 4 ),
+		precipFactor = ( ( precipBase - wateringData.precip ) * 200 );
+
+	// Apply adjustment options, if provided, by multiplying the percentage against the factor
+	if ( adjustmentOptions ) {
+		if ( adjustmentOptions.hasOwnProperty( "h" ) ) {
+			humidityFactor = humidityFactor * ( adjustmentOptions.h / 100 );
+		}
+
+		if ( adjustmentOptions.hasOwnProperty( "t" ) ) {
+			tempFactor = tempFactor * ( adjustmentOptions.t / 100 );
+		}
+
+		if ( adjustmentOptions.hasOwnProperty( "r" ) ) {
+			precipFactor = precipFactor * ( adjustmentOptions.r / 100 );
+		}
+	}
+
+	// Apply all of the weather modifying factors and clamp the result between 0 and 200%.
+	return Math.floor( Math.min( Math.max( 0, 100 + humidityFactor + tempFactor + precipFactor ), 200 ) );
 }
 
 /**
@@ -281,27 +280,30 @@ export const getWateringData = async function( req: express.Request, res: expres
 		}
 	}
 
-	let scale: number = calculateWeatherScale( adjustmentMethod, adjustmentOptions, wateringData ),
-		rainDelay: number = -1;
+	let scale = -1,	rainDelay = -1;
+
+	if ( adjustmentMethod === ADJUSTMENT_METHOD.ZIMMERMAN ) {
+		scale = calculateZimmermanWateringScale( adjustmentOptions, wateringData );
+	}
 
 	if (wateringData) {
 		// Check for any user-set restrictions and change the scale to 0 if the criteria is met
 		if (checkWeatherRestriction(req.params[0], wateringData)) {
 			scale = 0;
 		}
-	}
 
-	// If any weather adjustment is being used, check the rain status
-	if ( adjustmentMethod > 0 && wateringData && wateringData.raining ) {
+		// If any weather adjustment is being used, check the rain status
+		if ( adjustmentMethod > 0 && wateringData.raining ) {
 
-		// If it is raining and the user has weather-based rain delay as the adjustment method then apply the specified delay
-		if ( adjustmentMethod === 2 ) {
+			// If it is raining and the user has weather-based rain delay as the adjustment method then apply the specified delay
+			if ( adjustmentMethod === ADJUSTMENT_METHOD.RAIN_DELAY ) {
 
-			rainDelay = ( adjustmentOptions && adjustmentOptions.hasOwnProperty( "d" ) ) ? adjustmentOptions.d : 24;
-		} else {
+				rainDelay = ( adjustmentOptions && adjustmentOptions.hasOwnProperty( "d" ) ) ? adjustmentOptions.d : 24;
+			} else {
 
-			// For any other adjustment method, apply a scale of 0 (as the scale will revert when the rain stops)
-			scale = 0;
+				// For any other adjustment method, apply a scale of 0 (as the scale will revert when the rain stops)
+				scale = 0;
+			}
 		}
 	}