diff --git a/CMakeLists.txt b/CMakeLists.txt
index 898a692..01c113f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -80,6 +80,7 @@ SET(SOURCE
     src/behave/palmettoGallberry.cpp
     src/behave/randfuel.cpp
     src/behave/randthread.cpp
+    src/behave/relativeHumidity.cpp
     src/behave/safety.cpp
     src/behave/slopeTool.cpp
     src/behave/species_master_table.cpp
@@ -121,6 +122,7 @@ SET(HEADERS
     src/behave/palmettoGallberry.h
     src/behave/randfuel.h
     src/behave/randthread.h
+    src/behave/relativeHumidity.h
     src/behave/safety.h
     src/behave/slopeTool.h
     src/behave/species_master_table.h
diff --git a/src/behave/relativeHumidity.cpp b/src/behave/relativeHumidity.cpp
new file mode 100644
index 0000000..3c695c7
--- /dev/null
+++ b/src/behave/relativeHumidity.cpp
@@ -0,0 +1,135 @@
+#include <math.h>
+#include "relativeHumidity.h"
+
+// Constructors
+RelativeHumidityTool::RelativeHumidityTool() {
+  dryBulbTemperature_ = 0.;
+  wetBulbTemperature_ = 0.;
+  siteElevation_ = 0.;
+  wetBulbDepression_ = 0.;
+  dewPointTemperature_ = 0.;
+  relativeHumidity_ = 0.;
+}
+
+RelativeHumidityTool::RelativeHumidityTool(const RelativeHumidityTool &rhs) {
+  memberwiseCopyAssignment(rhs);
+}
+
+RelativeHumidityTool& RelativeHumidityTool::operator=(const RelativeHumidityTool& rhs) {
+    if (this != &rhs) {
+        memberwiseCopyAssignment(rhs);
+    }
+    return *this;
+}
+
+void RelativeHumidityTool::memberwiseCopyAssignment(const RelativeHumidityTool& rhs)
+{
+  dryBulbTemperature_ = rhs.dryBulbTemperature_;
+  wetBulbTemperature_ = rhs.wetBulbTemperature_;
+  siteElevation_ = rhs.siteElevation_;
+
+  wetBulbDepression_ = rhs.wetBulbDepression_;
+  dewPointTemperature_ = rhs.dewPointTemperature_;
+  relativeHumidity_ = rhs.relativeHumidity_;
+}
+
+RelativeHumidityTool::~RelativeHumidityTool() {}
+
+// Calculate
+void RelativeHumidityTool::calculate() {
+  double dryBulbTemp = TemperatureUnits::fromBaseUnits(dryBulbTemperature_, TemperatureUnits::Celsius);
+  double wetBulbTemp = TemperatureUnits::fromBaseUnits(wetBulbTemperature_, TemperatureUnits::Celsius);
+  double siteElevation = LengthUnits::fromBaseUnits(siteElevation_, LengthUnits::Meters);
+
+  // Calculate Dew Point
+  double dewPointTemp = dryBulbTemp;
+
+  if ( wetBulbTemp < dryBulbTemp ) {
+
+    double e2 = 6.1121 * exp( 17.502 * wetBulbTemp / (240.97 + wetBulbTemp) );
+
+    if ( wetBulbTemp < 0. ) {
+      e2 = 6.1115 * exp( 22.452 * wetBulbTemp / ( 272.55 + wetBulbTemp) );
+    }
+
+    double p = 1013. * exp( -0.0000375 * siteElevation);
+    double d = 0.66 * ( 1. + 0.00115 * wetBulbTemp) * (dryBulbTemp - wetBulbTemp);
+    double e3 = e2 - d * p / 1000.;
+
+    if ( e3 < 0.001 ) {
+      e3 = 0.001;
+    }
+
+    dewPointTemp = -240.97 /  ( 1.- 17.502 / log(e3 / 6.1121) );
+
+    if ( dewPointTemp < -40. ) {
+      dewPointTemp = -40.;
+    }
+  }
+
+  // Calculate Relative Humidity
+  double relativeHumidity = 0.;
+
+  // Convert to Fahrenheit
+  double dewPointTempF = dewPointTemp * 9. / 5. + 32.0;
+  double dryBulbTempF = dryBulbTemp * 9. / 5. + 32.0;
+
+  if ( dewPointTempF >= dryBulbTempF ) {
+    relativeHumidity = 1.0;
+  } else {
+    relativeHumidity = exp( -7469. / ( dewPointTempF + 398.0 ) + 7469. / ( dryBulbTempF + 398.0 ) );
+  }
+
+  // Store results
+  dewPointTemperature_ = TemperatureUnits::toBaseUnits(dewPointTemp, TemperatureUnits::Celsius);
+  relativeHumidity_ = FractionUnits::toBaseUnits(relativeHumidity, FractionUnits::Fraction);
+}
+
+// Getters
+double RelativeHumidityTool::getDryBulbTemperature(TemperatureUnits::TemperatureUnitsEnum temperatureUnits) {
+  return TemperatureUnits::fromBaseUnits(dryBulbTemperature_, temperatureUnits);
+}
+
+double RelativeHumidityTool::getWetBulbTemperature(TemperatureUnits::TemperatureUnitsEnum temperatureUnits) {
+  return TemperatureUnits::fromBaseUnits(wetBulbTemperature_, temperatureUnits);
+}
+
+double RelativeHumidityTool::getSiteElevation(LengthUnits::LengthUnitsEnum lengthUnits) {
+  return LengthUnits::fromBaseUnits(siteElevation_, lengthUnits);
+}
+
+double RelativeHumidityTool::getWetBulbDepression(TemperatureUnits::TemperatureUnitsEnum temperatureUnits) {
+  double dryBulbTemp = TemperatureUnits::fromBaseUnits(dryBulbTemperature_, TemperatureUnits::Celsius);
+  double wetBulbTemp = TemperatureUnits::fromBaseUnits(wetBulbTemperature_, TemperatureUnits::Celsius);
+
+  double wetBulbDep = dryBulbTemp - wetBulbTemp;
+
+  if (temperatureUnits == TemperatureUnits::Celsius) {
+    return wetBulbDep;
+  } else {
+    return wetBulbDep * 1.8;
+  }
+
+}
+
+double RelativeHumidityTool::getDewPointTemperature(TemperatureUnits::TemperatureUnitsEnum temperatureUnits) {
+  return TemperatureUnits::fromBaseUnits(dewPointTemperature_, temperatureUnits);
+}
+
+double RelativeHumidityTool::getRelativeHumidity(FractionUnits::FractionUnitsEnum fractionUnits) {
+  return FractionUnits::fromBaseUnits(relativeHumidity_, fractionUnits);
+}
+
+// Setters
+void RelativeHumidityTool::setDryBulbTemperature(double dryBulbTemperature, TemperatureUnits::TemperatureUnitsEnum temperatureUnits) {
+    dryBulbTemperature_ = TemperatureUnits::toBaseUnits(dryBulbTemperature, temperatureUnits);
+}
+
+void RelativeHumidityTool::setWetBulbTemperature(double wetBulbTemperature, TemperatureUnits::TemperatureUnitsEnum temperatureUnits) {
+    wetBulbTemperature_ = TemperatureUnits::toBaseUnits(wetBulbTemperature, temperatureUnits);
+}
+
+void RelativeHumidityTool::setSiteElevation(double siteElevation, LengthUnits::LengthUnitsEnum lengthUnits) {
+    siteElevation_ = LengthUnits::toBaseUnits(siteElevation, lengthUnits);
+}
+
diff --git a/src/behave/relativeHumidity.h b/src/behave/relativeHumidity.h
new file mode 100644
index 0000000..9d61412
--- /dev/null
+++ b/src/behave/relativeHumidity.h
@@ -0,0 +1,47 @@
+#pragma once
+#include "behaveUnits.h"
+
+class RelativeHumidityTool {
+public:
+
+  // Constructors
+  RelativeHumidityTool();
+  RelativeHumidityTool(const RelativeHumidityTool& rhs);
+  RelativeHumidityTool& operator=(const RelativeHumidityTool& rhs);
+
+  // Destructors
+  ~RelativeHumidityTool();
+
+  // Calculate
+  void calculate();
+
+  // Getters
+  double getDryBulbTemperature(TemperatureUnits::TemperatureUnitsEnum temperatureUnits);
+  double getSiteElevation(LengthUnits::LengthUnitsEnum lengthUnits);
+  double getWetBulbTemperature(TemperatureUnits::TemperatureUnitsEnum temperatureUnits);
+
+  double getDewPointTemperature(TemperatureUnits::TemperatureUnitsEnum temperatureUnits);
+  double getRelativeHumidity(FractionUnits::FractionUnitsEnum fractionUnits);
+  double getWetBulbDepression(TemperatureUnits::TemperatureUnitsEnum temperatureUnits);
+
+  // Setters
+  void setDryBulbTemperature(double dryBulbTemperature, TemperatureUnits::TemperatureUnitsEnum temperatureUnits);
+  void setSiteElevation(double siteElevation, LengthUnits::LengthUnitsEnum lengthUnits);
+  void setWetBulbTemperature(double wetBulbTemperature, TemperatureUnits::TemperatureUnitsEnum temperatureUnits);
+
+
+protected:
+  void memberwiseCopyAssignment(const RelativeHumidityTool& rhs);
+
+  // Input Variables
+  double dryBulbTemperature_ = 0;
+  double siteElevation_ = 0;
+  double wetBulbTemperature_ = 0;
+
+  // Output Variables
+  double dewPointTemperature_ = 0;
+  double relativeHumidity_ = 0;
+  double wetBulbDepression_ = 0;
+};
+
+