diff --git a/resources/model/OpenStudio.idd b/resources/model/OpenStudio.idd
index d1cadd46d3..e6f81890c0 100644
--- a/resources/model/OpenStudio.idd
+++ b/resources/model/OpenStudio.idd
@@ -1669,8 +1669,19 @@ OS:WeatherFile,
   A7, \field Url
        \retaincase
        \type url
-  A8; \field Checksum
+  A8, \field Checksum
        \type alpha
+  A9, \field Start Date Actual Year
+      \type integer
+  A10; \field Start Day of Week
+       \type choice
+       \key Sunday
+       \key Monday
+       \key Tuesday
+       \key Wednesday
+       \key Thursday
+       \key Friday
+       \key Saturday
 
 OS:WeatherProperty:SkyTemperature,
        \memo This object is used to override internal sky temperature calculations.
diff --git a/src/model/WeatherFile.cpp b/src/model/WeatherFile.cpp
index f7be9347f5..5a5f4352b2 100644
--- a/src/model/WeatherFile.cpp
+++ b/src/model/WeatherFile.cpp
@@ -39,6 +39,7 @@
 #include <utilities/idd/IddEnums.hxx>
 
 #include "../utilities/filetypes/EpwFile.hpp"
+#include "../utilities/time/Date.hpp"
 #include "../utilities/core/Assert.hpp"
 #include "../utilities/core/PathHelpers.hpp"
 #include "../utilities/core/String.hpp"
@@ -375,6 +376,19 @@ namespace model {
       return types;
     }
 
+    boost::optional<int> WeatherFile_Impl::startDateActualYear() const {
+      boost::optional<int> result = getInt(OS_WeatherFileFields::StartDateActualYear, true);
+      return result;
+    }
+
+    boost::optional<DayOfWeek> WeatherFile_Impl::startDayOfWeek() const {
+      boost::optional<std::string> result = getString(OS_WeatherFileFields::StartDayofWeek, false, true);
+      if (!result) {
+        return boost::none;
+      }
+      return openstudio::DayOfWeek{*result};
+    }
+
   }  // namespace detail
 
   IddObjectType WeatherFile::iddObjectType() {
@@ -395,6 +409,12 @@ namespace model {
     weatherFile.setDouble(OS_WeatherFileFields::Elevation, epwFile.elevation());
     weatherFile.setString(OS_WeatherFileFields::Url, toString(epwFile.path()));
     weatherFile.setString(OS_WeatherFileFields::Checksum, epwFile.checksum());
+    if (auto s_ = epwFile.startDateActualYear()) {
+      weatherFile.setInt(OS_WeatherFileFields::StartDateActualYear, s_.get());
+    }
+
+    weatherFile.setString(OS_WeatherFileFields::StartDayofWeek, epwFile.startDayOfWeek().valueName());
+
     return weatherFile;
   }
 
@@ -535,6 +555,14 @@ void WeatherFile::resetChecksum() {
     return getImpl<detail::WeatherFile_Impl>()->environmentName();
   }
 
+  boost::optional<int> WeatherFile::startDateActualYear() const {
+    return getImpl<detail::WeatherFile_Impl>()->startDateActualYear();
+  }
+
+  boost::optional<DayOfWeek> WeatherFile::startDayOfWeek() const {
+    return getImpl<detail::WeatherFile_Impl>()->startDayOfWeek();
+  }
+
   /// @cond
   WeatherFile::WeatherFile(std::shared_ptr<detail::WeatherFile_Impl> impl) : ModelObject(std::move(impl)) {}
   WeatherFile::WeatherFile(Model& model) : ModelObject(WeatherFile::iddObjectType(), model) {}
diff --git a/src/model/WeatherFile.hpp b/src/model/WeatherFile.hpp
index 20626f4d15..ebc9276997 100644
--- a/src/model/WeatherFile.hpp
+++ b/src/model/WeatherFile.hpp
@@ -38,6 +38,7 @@
 namespace openstudio {
 
 class EpwFile;
+class DayOfWeek;
 
 namespace model {
 
@@ -105,6 +106,10 @@ namespace model {
 
     boost::optional<std::string> checksum() const;
 
+    boost::optional<int> startDateActualYear() const;
+
+    boost::optional<DayOfWeek> startDayOfWeek() const;
+
     //@}
     /** @name Setters */
     //@{
diff --git a/src/model/WeatherFile_Impl.hpp b/src/model/WeatherFile_Impl.hpp
index 77ef4a3834..cd3a0965c4 100644
--- a/src/model/WeatherFile_Impl.hpp
+++ b/src/model/WeatherFile_Impl.hpp
@@ -38,6 +38,7 @@
 namespace openstudio {
 
 class EpwFile;
+class DayOfWeek;
 
 namespace model {
 
@@ -74,6 +75,10 @@ namespace model {
 
       virtual IddObjectType iddObjectType() const override;
 
+      virtual std::vector<EMSActuatorNames> emsActuatorNames() const override;
+
+      virtual std::vector<std::string> emsInternalVariableNames() const override;
+
       /** @name Getters */
       //@{
 
@@ -103,9 +108,9 @@ namespace model {
 
       boost::optional<std::string> checksum() const;
 
-      virtual std::vector<EMSActuatorNames> emsActuatorNames() const override;
+      boost::optional<int> startDateActualYear() const;
 
-      virtual std::vector<std::string> emsInternalVariableNames() const override;
+      boost::optional<DayOfWeek> startDayOfWeek() const;
 
       //@}
       /** @name Setters */
diff --git a/src/model/YearDescription.cpp b/src/model/YearDescription.cpp
index 673499bc03..a913067da2 100644
--- a/src/model/YearDescription.cpp
+++ b/src/model/YearDescription.cpp
@@ -228,11 +228,25 @@ namespace model {
 
       std::string dayofWeekforStartDay = this->dayofWeekforStartDay();
       if (!dayofWeekforStartDay.empty()) {
-        try {
+        if (istringEqual(dayofWeekforStartDay, "UseWeatherFile")) {
+          if (auto weatherFile_ = this->model().weatherFile()) {
+            if (auto epwStartYear = weatherFile_->startDateActualYear()) {
+              LOG(Info, "YearDescription::assumedYear: using the WeatherFile startDateActualYear = " << epwStartYear.get());
+              return epwStartYear.get();
+            } else if (boost::optional<openstudio::DayOfWeek> dow_ = weatherFile_->startDayOfWeek()) {
+              auto dow = dow_.get();
+              LOG(Info, "assumedYear: using the WeatherFile startDayOfWeek = " << dow);
+              yd.yearStartsOnDayOfWeek = dow;
+            } else {
+              LOG(Error, "'UseWeatherFile' is selected in YearDescription"
+                           << " but the WeatherFile has neither an actual start year nor a Start Day of Week");
+            }
+          } else {
+            LOG(Error, "'UseWeatherFile' is selected in YearDescription, but there are no weather file set for the model.");
+          }
+        } else {
           openstudio::DayOfWeek dow(dayofWeekforStartDay);
           yd.yearStartsOnDayOfWeek = dow;
-        } catch (const std::exception&) {
-          LOG(Error, "'" << dayofWeekforStartDay << "' is not yet a supported option for YearDescription");
         }
       }
 
@@ -240,26 +254,12 @@ namespace model {
     }
 
     openstudio::Date YearDescription_Impl::makeDate(openstudio::MonthOfYear monthOfYear, unsigned dayOfMonth) {
-      boost::optional<int> calendarYear = this->calendarYear();
-      if (calendarYear) {
-        return openstudio::Date(monthOfYear, dayOfMonth, *calendarYear);
-      }
-
-      openstudio::YearDescription yd;
-
-      yd.isLeapYear = this->isLeapYear();
-
-      std::string dayofWeekforStartDay = this->dayofWeekforStartDay();
-      if (!dayofWeekforStartDay.empty()) {
-        if (istringEqual(dayofWeekforStartDay, "UseWeatherFile")) {
-          LOG(Info, "'UseWeatherFile' is not yet a supported option for YearDescription");
-        } else {
-          openstudio::DayOfWeek dow(dayofWeekforStartDay);
-          yd.yearStartsOnDayOfWeek = dow;
-        }
+      boost::optional<int> year = this->calendarYear();
+      if (!year) {
+        year = this->assumedYear();
       }
 
-      return openstudio::Date(monthOfYear, dayOfMonth, yd);
+      return openstudio::Date(monthOfYear, dayOfMonth, *year);
     }
 
     openstudio::Date YearDescription_Impl::makeDate(unsigned monthOfYear, unsigned dayOfMonth) {
diff --git a/src/model/test/WeatherFile_GTest.cpp b/src/model/test/WeatherFile_GTest.cpp
index 3673e7107a..5efe01cfa7 100644
--- a/src/model/test/WeatherFile_GTest.cpp
+++ b/src/model/test/WeatherFile_GTest.cpp
@@ -32,8 +32,11 @@
 #include "ModelFixture.hpp"
 #include "../WeatherFile.hpp"
 #include "../WeatherFile_Impl.hpp"
+#include "../YearDescription.hpp"
+#include "../YearDescription_Impl.hpp"
 #include "../Model.hpp"
 #include "../Model_Impl.hpp"
+#include "../../utilities/filetypes/EpwFile.hpp"
 
 using namespace openstudio;
 using namespace openstudio::model;
@@ -42,6 +45,126 @@ using std::string;
 TEST_F(ModelFixture, WeatherFile) {
   Model model;
   EXPECT_FALSE(model.getOptionalUniqueModelObject<WeatherFile>());
-  model.getUniqueModelObject<WeatherFile>();
+  auto weatherFile = model.getUniqueModelObject<WeatherFile>();
   EXPECT_TRUE(model.getOptionalUniqueModelObject<WeatherFile>());
+  EXPECT_FALSE(weatherFile.startDateActualYear());
+  EXPECT_FALSE(weatherFile.startDayOfWeek());
+}
+
+TEST_F(ModelFixture, WeatherFile_assign_TMY) {
+
+  Model model;
+  auto yd = model.getUniqueModelObject<openstudio::model::YearDescription>();
+  EXPECT_FALSE(yd.calendarYear());
+  EXPECT_EQ(2009, yd.assumedYear());
+
+  auto epwPath = resourcesPath() / "utilities/Filetypes/USA_CO_Golden-NREL.724666_TMY3.epw";
+  EpwFile epwFile(epwPath);
+  EXPECT_TRUE(WeatherFile::setWeatherFile(model, epwFile));
+
+  EXPECT_FALSE(epwFile.isActual());
+  EXPECT_FALSE(epwFile.startDateActualYear());
+  EXPECT_EQ(DayOfWeek{"Sunday"}, epwFile.startDayOfWeek());
+
+  EXPECT_FALSE(yd.calendarYear());
+  EXPECT_EQ(2006, yd.assumedYear());
+  ASSERT_TRUE(model.weatherFile());
+
+  auto weatherFile = model.weatherFile().get();
+  // This is a TMY, so no actual start date
+  EXPECT_FALSE(weatherFile.startDateActualYear());
+  ASSERT_TRUE(weatherFile.startDayOfWeek());
+  EXPECT_EQ(epwFile.startDayOfWeek(), weatherFile.startDayOfWeek().get());
+}
+
+TEST_F(ModelFixture, WeatherFile_assign_AMY) {
+
+  Model model;
+  auto yd = model.getUniqueModelObject<openstudio::model::YearDescription>();
+  EXPECT_FALSE(yd.calendarYear());
+  EXPECT_EQ(2009, yd.assumedYear());
+
+  auto epwPath = resourcesPath() / "utilities/Filetypes/USA_CO_Golden-NREL.amy";
+  EpwFile epwFile(epwPath);
+  EXPECT_TRUE(WeatherFile::setWeatherFile(model, epwFile));
+
+  EXPECT_TRUE(epwFile.isActual());
+  ASSERT_TRUE(epwFile.startDateActualYear());
+  EXPECT_EQ(DayOfWeek{"Friday"}, epwFile.startDayOfWeek());
+
+  EXPECT_FALSE(yd.calendarYear());
+  EXPECT_EQ(1999, yd.assumedYear());
+  ASSERT_TRUE(model.weatherFile());
+
+  auto weatherFile = model.weatherFile().get();
+  // This is a TMY, so no actual start date
+  ASSERT_TRUE(weatherFile.startDateActualYear());
+  EXPECT_EQ(1999, weatherFile.startDateActualYear().get());
+
+  ASSERT_TRUE(weatherFile.startDayOfWeek());
+  EXPECT_EQ(epwFile.startDayOfWeek(), weatherFile.startDayOfWeek().get());
+}
+
+TEST_F(ModelFixture, prout) {
+
+  // A TMY, with start day set to Tuesday (see DATA PERIODS line)
+  std::string epwFileStringNoYear = R"(LOCATION,Denver Centennial  Golden   Nr,CO,USA,TMY3,724666,39.74,-105.18,-7.0,1829.0
+DESIGN CONDITIONS,1,Climate Design Data 2009 ASHRAE Handbook,,Heating,12,-18.8,-15.5,-21.6,0.7,-10.9,-18.8,0.9,-7.5,12.2,3.9,10.9,3.8,3,340,Cooling,7,15.2,33,15.7,32,15.5,30.2,15.3,18.4,27.3,17.5,26.4,16.8,25.6,4.9,0,16.1,14.3,20.2,14.9,13.2,19.9,13.9,12.3,19.6,59.7,27.3,56.6,26.6,54,25.7,760,Extremes,11.1,9.5,8.4,22.9,-22.9,36.1,3.8,1.2,-25.7,37,-27.9,37.7,-30.1,38.3,-32.8,39.2
+TYPICAL/EXTREME PERIODS,6,Summer - Week Nearest Max Temperature For Period,Extreme,7/ 6,7/12,Summer - Week Nearest Average Temperature For Period,Typical,7/27,8/ 2,Winter - Week Nearest Min Temperature For Period,Extreme,12/15,12/21,Winter - Week Nearest Average Temperature For Period,Typical,12/ 1,12/ 7,Autumn - Week Nearest Average Temperature For Period,Typical,10/20,10/26,Spring - Week Nearest Average Temperature For Period,Typical,4/26,5/ 2
+GROUND TEMPERATURES,3,.5,,,,-0.60,1.34,5.12,8.69,15.46,19.02,20.00,18.20,14.02,8.83,3.71,0.32,2,,,,2.08,2.55,4.70,7.10,12.30,15.62,17.28,16.91,14.53,10.94,6.90,3.72,4,,,,4.84,4.51,5.45,6.81,10.25,12.82,14.49,14.90,13.86,11.74,9.00,6.53
+HOLIDAYS/DAYLIGHT SAVINGS,No,0,0,0
+COMMENTS 1,Custom/User Format -- WMO#724666; NREL TMY Data Set (2008); Period of Record 1973-2005 (Generally)
+COMMENTS 2, -- Ground temps produced with a standard soil diffusivity of 2.3225760E-03 {m**2/day}
+DATA PERIODS,1,1,Data,Tuesday, 1/ 1,1/1
+1999,1,1,1,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9*9*9,-3.0,-4.0,92,80600,0,0,257,0,0,0,0,0,0,0,0,0.0,9,8,16.1,3300,9,999999999,89,0.0310,0,88,0.330,999.0,99.0
+2005,1,1,2,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9*9*9,-3.0,-6.0,77,80600,0,0,261,0,0,0,0,0,0,0,170,2.1,10,9,16.1,3000,9,999999999,89,0.0310,0,88,0.330,999.0,99.0
+1999,1,1,3,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9*9*9,-4.0,-7.0,77,80700,0,0,251,0,0,0,0,0,0,0,250,1.5,9,8,16.1,3000,9,999999999,89,0.0310,0,88,0.330,999.0,99.0
+1999,1,1,4,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9*9*9,-2.0,-5.0,78,80700,0,0,273,0,0,0,0,0,0,0,330,1.5,10,10,16.1,2700,9,999999999,89,0.0310,0,88,0.330,999.0,99.0
+1999,1,1,5,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9?9?9,-2.0,-4.0,85,80800,0,0,274,0,0,0,0,0,0,0,240,3.6,10,10,12.9,1080,9,999999999,100,0.0310,0,88,0.330,0.0,1.0
+1999,1,1,6,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9*9*9,-1.0,-2.0,92,80900,0,0,280,0,0,0,0,0,0,0,0,0.0,10,10,1.2,150,9,999999999,89,0.0310,0,88,0.330,999.0,99.0
+1999,1,1,7,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9*9*9,-1.0,-1.0,100,81000,0,0,281,0,0,0,0,0,0,0,270,2.6,10,10,1.6,480,9,999999999,89,0.0310,0,88,0.330,999.0,99.0
+1999,1,1,8,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9?9?9,-1.0,-1.0,100,81100,41,861,281,4,119,2,906,6725,559,79,260,2.1,10,10,1.6,480,9,999999999,89,0.0310,0,88,0.330,0.0,1.0
+1999,1,1,9,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9*9*9,0.0,-1.0,92,81300,242,1415,272,178,480,95,17449,32960,11774,1860,240,2.6,9,8,6.4,1500,9,999999999,89,0.0310,0,88,0.330,999.0,99.0
+1999,1,1,10,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9*9*9,2.0,-1.0,80,81500,429,1415,294,49,0,49,5871,0,5871,2108,280,2.6,10,10,16.1,1500,9,999999999,89,0.0310,0,88,0.330,999.0,99.0
+1999,1,1,11,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9?9?9,2.0,-1.0,80,81500,563,1415,294,431,654,169,44097,62425,19149,3410,10,4.6,10,10,16.1,1500,9,999999999,89,0.0310,0,88,0.330,0.0,6.0
+1999,1,1,12,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9*9*9,1.0,-2.0,79,81500,635,1415,275,326,296,193,34655,30037,21116,4256,10,7.2,8,8,16.1,1500,9,999999999,80,0.0310,0,88,0.330,999.0,99.0
+1999,1,1,13,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9*9*9,3.0,-3.0,63,81600,640,1415,296,255,96,212,28023,9483,23716,5980,360,6.2,10,10,16.1,810,9,999999999,80,0.0310,0,88,0.330,999.0,99.0
+1999,1,1,14,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9?9?9,2.0,-4.0,62,81600,577,1415,291,160,12,155,18096,900,17727,5938,20,7.2,10,10,16.1,960,9,999999999,80,0.0310,0,88,0.330,0.0,1.0
+1999,1,1,15,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9?9?9,1.0,-4.0,67,81700,452,1415,287,59,0,59,7007,0,7007,2516,20,7.2,10,10,12.9,840,9,999999999,80,0.0310,0,88,0.330,0.0,1.0
+1999,1,1,16,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9?9?9,1.0,-4.0,67,81700,272,1415,287,51,0,51,5821,0,5821,1885,360,5.1,10,10,16.1,1020,9,999999999,80,0.0310,0,88,0.330,0.0,1.0
+1999,1,1,17,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9*9?9?9?9*9*9?9*9*9,0.0,-3.9,72,81700,62,1073,283,18,170,12,2390,7964,1886,227,10,5.4,10,10,16.1,885,9,999999999,80,0.0310,0,88,0.330,999.0,99.0
+1999,1,1,18,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9?9?9,-1.0,-4.0,78,81800,0,0,278,0,0,0,0,0,0,0,10,5.7,10,10,12.9,750,9,999999999,80,0.0310,0,88,0.330,0.0,1.0
+1999,1,1,19,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9*9*9,-2.0,-6.0,71,81800,0,0,272,0,0,0,0,0,0,0,360,5.1,10,10,14.5,750,9,999999999,69,0.0310,0,88,0.330,999.0,99.0
+1999,1,1,20,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9?9?9,-4.0,-8.0,71,81800,0,0,262,0,0,0,0,0,0,0,20,8.2,10,10,14.5,480,9,999999999,69,0.0310,0,88,0.330,0.0,1.0
+1999,1,1,21,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9?9?9,-5.0,-7.0,84,81800,0,0,260,0,0,0,0,0,0,0,10,5.1,10,10,2.8,330,9,999999999,69,0.0310,0,88,0.330,0.0,1.0
+1999,1,1,22,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9?9?9,-6.0,-6.0,100,81800,0,0,257,0,0,0,0,0,0,0,10,3.6,10,10,1.2,210,9,999999999,69,0.0310,0,88,0.330,0.0,1.0
+1999,1,1,23,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9*9*9,-7.0,-9.0,84,81800,0,0,250,0,0,0,0,0,0,0,30,6.7,10,10,1.2,150,9,999999999,69,0.0310,0,88,0.330,999.0,99.0
+1999,1,1,24,0,?9?9?9?9E0?9?9?9?9?9?9?9?9?9?9?9?9?9?9?9*9*9?9*9*9,-7.0,-9.0,84,81700,0,0,250,0,0,0,0,0,0,0,30,6.7,10,10,1.2,150,9,999999999,69,0.0310,0,88,0.330,999.0,99.0
+)";
+
+  boost::optional<EpwFile> epwFile_ = EpwFile::loadFromString(epwFileStringNoYear);
+  ASSERT_TRUE(epwFile_);
+  auto epwFile = epwFile_.get();
+
+  Model model;
+  auto yd = model.getUniqueModelObject<openstudio::model::YearDescription>();
+  EXPECT_FALSE(yd.calendarYear());
+  EXPECT_EQ(2009, yd.assumedYear());
+
+  EXPECT_TRUE(WeatherFile::setWeatherFile(model, epwFile));
+
+  EXPECT_FALSE(epwFile.isActual());
+  EXPECT_FALSE(epwFile.startDateActualYear());
+  EXPECT_EQ(DayOfWeek{"Tuesday"}, epwFile.startDayOfWeek());
+
+  EXPECT_FALSE(yd.calendarYear());
+  EXPECT_EQ(2002, yd.assumedYear());
+  ASSERT_TRUE(model.weatherFile());
+
+  auto weatherFile = model.weatherFile().get();
+  // This is a TMY, so no actual start date
+  EXPECT_FALSE(weatherFile.startDateActualYear());
+
+  ASSERT_TRUE(weatherFile.startDayOfWeek());
+  EXPECT_EQ(epwFile.startDayOfWeek(), weatherFile.startDayOfWeek().get());
 }