How can I deal with rapid fluctuation of Anemometer readings?
A:  Use a running average

In the initialization I include an array to hold 10 values

// Wind Speed Anemometer
const int sensorPin = A3;
int sensorValue = 0;
float sensorVoltage = 0;
float windSpeed = 0;
float voltageConversionConstant = 0.004887586;  // (5/1024)
float voltageMin = .33;   // 0.4 in the documentation
float windSpeedMin = 0;
float voltageMax = 1.5;   // 2.0 in the documentation
float windSpeedMax = 32;

float ws[10] = { };      // (initializes all to zero)
int wsIndex = 0;
float wsTot = 0.0;
float wsDisplay = 0.0;


Then in the Loop I fill the array with values and display the average of the 10 readings stored there

  // Wind Speed
  sensorValue = analogRead(sensorPin); 
  sensorVoltage = sensorValue * voltageConversionConstant;
  if (sensorVoltage &lt;= voltageMin) windSpeed = 0; 
  else windSpeed = ((sensorVoltage-voltageMin)*windSpeedMax /(voltageMax-voltageMin)*2.23694); 

  if (wsIndex&lt;9) {
    ws[wsIndex] = windSpeed;
    wsIndex++;
    }
  else {
    wsTot = 0.0;
    for (int i=0;i&lt;=9;i++) wsTot = wsTot + ws[i];
    wsDisplay = wsTot / 10.0;
    lcd.setCursor(0,3);
    lcd.print(wsDisplay);
    lcd.print(" MPH  "); 
    wsIndex = 0;
    ws[wsIndex] = windSpeed;
    }