diff --git a/forecastmanager/forecast_settings.py b/forecastmanager/forecast_settings.py
index 43e2b1a..de57ab3 100644
--- a/forecastmanager/forecast_settings.py
+++ b/forecastmanager/forecast_settings.py
@@ -13,14 +13,14 @@
 from wagtail.contrib.settings.registry import register_setting
 from wagtail.models import Orderable
 
-from forecastmanager.constants import WEATHER_PARAMETER_CHOICES, WEATHER_PARAMETERS_AS_DICT
-from forecastmanager.widgets import WeatherSymbolChooserWidget
+from forecastmanager.constants import WEATHER_PARAMETERS_AS_DICT
+from forecastmanager.widgets import WeatherSymbolChooserWidget, DataParameterWidget
 
 
 @register_setting
 class ForecastSetting(ClusterableModel, BaseSiteSetting):
     enable_auto_forecast = models.BooleanField(default=False, verbose_name=_('Enable automated forecasts'))
-    default_city = models.ForeignKey("City", blank=True, null=True, on_delete=models.CASCADE,
+    default_city = models.ForeignKey("City", blank=True, null=True, on_delete=models.SET_NULL,
                                      verbose_name=_("Default City"))
     weather_detail_page = models.ForeignKey("wagtailcore.Page", blank=True, null=True, on_delete=models.SET_NULL, )
     weather_reports_page = models.ForeignKey("wagtailcore.Page", blank=True, null=True, on_delete=models.SET_NULL,
@@ -98,12 +98,11 @@ def save(self, *args, **kwargs):
 class ForecastDataParameters(Orderable):
     PARAMETER_TYPE_CHOICES = (
         ("numeric", _("Number")),
-        ("time", _("Time")),
         ("text", _("Text")),
     )
     parent = ParentalKey(ForecastSetting, on_delete=models.CASCADE, related_name="data_parameters")
-    parameter = models.CharField(max_length=100, choices=WEATHER_PARAMETER_CHOICES, unique=True,
-                                 verbose_name=_("Parameter"))
+    use_known_parameters = models.BooleanField(default=True, verbose_name=_("Use predefined parameters"))
+    parameter = models.CharField(max_length=100, unique=True, verbose_name=_("Parameter"))
     name = models.CharField(max_length=100, verbose_name=_("Parameter Label"),
                             help_text=_("Parameter name as locally labelled"))
     parameter_type = models.CharField(max_length=100, choices=PARAMETER_TYPE_CHOICES, verbose_name=_("Parameter Type"),
@@ -112,31 +111,32 @@ class ForecastDataParameters(Orderable):
                                       help_text="e.g °C, %, mm, hPa, etc ")
 
     panels = [
-        FieldPanel('parameter'),
+        FieldPanel('use_known_parameters'),
+        FieldPanel('parameter', widget=DataParameterWidget),
         FieldPanel('name'),
+        FieldPanel('parameter_type'),
+        FieldPanel('parameter_unit'),
     ]
 
     def __str__(self):
         return self.name
 
     @property
-    def parameter_info(self):
-        return WEATHER_PARAMETERS_AS_DICT.get(self.parameter)
+    def units(self):
+        if self.parameter_unit:
+            return self.parameter_unit
 
-    def parse_value(self, value):
-        info = self.parameter_info
+        if self.parameter_info:
+            return self.parameter_info.get("units")
 
-        if not info.get("data_type"):
-            return value
+        return None
 
-        try:
-            if info.get("data_type") == "int":
-                return int(float(value))
-            elif info.get("data_type") == "float":
-                return float(value)
-        except ValueError:
-            pass
+    @property
+    def parameter_info(self):
+        return WEATHER_PARAMETERS_AS_DICT.get(self.parameter)
 
+    def parse_value(self, value):
+        # TODO: Implement parsing for different parameter types
         return value
 
 
diff --git a/forecastmanager/forms.py b/forecastmanager/forms.py
index f676f0b..c7ccdd7 100644
--- a/forecastmanager/forms.py
+++ b/forecastmanager/forms.py
@@ -97,12 +97,13 @@ def clean(self):
 
             # check parameters
             for param, value in params_data.items():
-                param = ForecastDataParameters.objects.filter(name=param).first()
-                if not param:
-                    self.add_error(None, f"Unknown parameter found in table data: {param}")
-                    return cleaned_data
+                if value:
+                    param = ForecastDataParameters.objects.filter(name=param).first()
+                    if not param:
+                        self.add_error(None, f"Unknown parameter found in table data: {param}")
+                        return cleaned_data
 
-                city_data["data_values"].append({"parameter": param, "value": value})
+                    city_data["data_values"].append({"parameter": param, "value": value})
 
             forecast_data.append(city_data)
             added_cities.append(city.id)
diff --git a/forecastmanager/migrations/0022_alter_forecastdataparameters_parameter_type_and_more.py b/forecastmanager/migrations/0022_alter_forecastdataparameters_parameter_type_and_more.py
new file mode 100644
index 0000000..a29fc55
--- /dev/null
+++ b/forecastmanager/migrations/0022_alter_forecastdataparameters_parameter_type_and_more.py
@@ -0,0 +1,24 @@
+# Generated by Django 4.2.3 on 2024-04-15 06:55
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('forecastmanager', '0021_forecastsetting_weather_reports_page'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='forecastdataparameters',
+            name='parameter_type',
+            field=models.CharField(choices=[('numeric', 'Number'), ('text', 'Text')], default='numeric', max_length=100, verbose_name='Parameter Type'),
+        ),
+        migrations.AlterField(
+            model_name='forecastsetting',
+            name='default_city',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, to='forecastmanager.city', verbose_name='Default City'),
+        ),
+    ]
diff --git a/forecastmanager/migrations/0023_forecastdataparameters_use_known_parameters.py b/forecastmanager/migrations/0023_forecastdataparameters_use_known_parameters.py
new file mode 100644
index 0000000..947976e
--- /dev/null
+++ b/forecastmanager/migrations/0023_forecastdataparameters_use_known_parameters.py
@@ -0,0 +1,18 @@
+# Generated by Django 4.2.3 on 2024-04-15 11:07
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('forecastmanager', '0022_alter_forecastdataparameters_parameter_type_and_more'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='forecastdataparameters',
+            name='use_known_parameters',
+            field=models.BooleanField(default=True, verbose_name='Use known parameters'),
+        ),
+    ]
diff --git a/forecastmanager/models.py b/forecastmanager/models.py
index b88ee6c..0af01e4 100644
--- a/forecastmanager/models.py
+++ b/forecastmanager/models.py
@@ -73,7 +73,7 @@ class Meta:
         unique_together = ("forecast_date", "effective_period")
         verbose_name = _("Forecast")
         verbose_name_plural = _("Forecasts")
-        ordering = ["forecast_date", "effective_period"]
+        ordering = ["-forecast_date", "effective_period"]
 
     panels = [
         FieldPanel("forecast_date"),
@@ -126,15 +126,22 @@ def effective_period(self):
     def data_values_dict(self):
         data_values = {}
         for data_value in self.data_values.all():
-            data_values[data_value.parameter.parameter] = {
+            parameter_info = data_value.parameter.parameter_info
+            val = {
                 "value": data_value.parsed_value,
                 "name": data_value.parameter.name,
-                "label": data_value.parameter.parameter_info.get("label"),
-                "units": data_value.parameter.parameter_info.get("unit"),
+                "label": data_value.parameter.name,
+                "units": data_value.parameter.units,
                 "value_with_units": data_value.value_with_units,
-                "icon": data_value.parameter.parameter_info.get("icon"),
             }
 
+            if parameter_info:
+                val.update({
+                    "icon": data_value.parameter.parameter_info.get("icon"),
+                })
+
+            data_values[data_value.parameter.parameter] = val
+
         # Group temperature values
         temperature = {}
         if "air_temperature_max" in data_values:
@@ -201,4 +208,10 @@ def parsed_value(self):
 
     @property
     def value_with_units(self):
-        return f"{self.parsed_value}{self.parameter.parameter_info.get('unit')}"
+        if not self.parsed_value:
+            return None
+
+        if not self.parameter.units:
+            return self.parsed_value
+
+        return f"{self.parsed_value} {self.parameter.units}"
diff --git a/forecastmanager/static/forecastmanager/js/forecast-data-parameter-widget.js b/forecastmanager/static/forecastmanager/js/forecast-data-parameter-widget.js
new file mode 100644
index 0000000..1f0b632
--- /dev/null
+++ b/forecastmanager/static/forecastmanager/js/forecast-data-parameter-widget.js
@@ -0,0 +1,52 @@
+function DataParameterWidget(id, initialValue) {
+    const inputId = '#' + id
+    this.input = $(inputId);
+
+    const parameterListSelectId = id + "_parameter_list"
+    this.parameterListSelectInput = $("#" + parameterListSelectId);
+
+    const useKnownParameterInputId = id.split("-parameter")[0] + "-use_known_parameters"
+    this.checkIsKnownParameterInput = $("#" + useKnownParameterInputId)
+
+    const that = this
+
+    this.checkIsKnownParameterInput.change(function () {
+        const checked = $(this).is(":checked")
+
+        if (checked) {
+            that.input.hide()
+            that.parameterListSelectInput.show()
+        } else {
+            that.input.show()
+            that.parameterListSelectInput.hide()
+        }
+
+    })
+
+    if (this.checkIsKnownParameterInput.is(":checked")) {
+        // clear any previous value
+        that.parameterListSelectInput.show()
+    } else {
+        that.input.show()
+    }
+
+    this.parameterListSelectInput.change(function () {
+        const selectedVal = $(this).val()
+        that.setState(selectedVal)
+    })
+}
+
+DataParameterWidget.prototype.setState = function (newState) {
+    this.input.val(newState);
+};
+
+DataParameterWidget.prototype.getState = function () {
+    return this.input.val();
+};
+
+DataParameterWidget.prototype.getValue = function () {
+    return this.input.val();
+};
+
+DataParameterWidget.prototype.focus = function () {
+}
\ No newline at end of file
diff --git a/forecastmanager/templates/forecastmanager/create_forecast.html b/forecastmanager/templates/forecastmanager/create_forecast.html
index e1f60c6..dafa4c4 100644
--- a/forecastmanager/templates/forecastmanager/create_forecast.html
+++ b/forecastmanager/templates/forecastmanager/create_forecast.html
@@ -199,7 +199,7 @@ <h2>Match Fields</h2>
                     },
                     ...this.parameters.map((p) => ({
                         type: p.parameter_type,
-                        allowEmpty: false,
+                        allowEmpty: true,
                         allowInvalid: false,
                     })),
                     {
diff --git a/forecastmanager/templates/forecastmanager/edit_forecast.html b/forecastmanager/templates/forecastmanager/edit_forecast.html
index cfe6d96..4549059 100644
--- a/forecastmanager/templates/forecastmanager/edit_forecast.html
+++ b/forecastmanager/templates/forecastmanager/edit_forecast.html
@@ -48,11 +48,13 @@ <h2>{{ city_forecast.city.name }}</h2>
                                      alt="">
                             </td>
                             {% for param in weather_parameters %}
-                                {% for data in city_forecast.data_values.all %}
-                                    {% if data.parameter.parameter == param.parameter %}
-                                        <td>{{ data.value_with_units }}</td>
-                                    {% endif %}
-                                {% endfor %}
+                                <td>
+                                    {% for data in city_forecast.data_values.all %}
+                                        {% if data.parameter.parameter == param.parameter %}
+                                            {{ data.value_with_units }}
+                                        {% endif %}
+                                    {% endfor %}
+                                </td>
                             {% endfor %}
                         </tr>
                     {% endfor %}
diff --git a/forecastmanager/templates/forecastmanager/forecast_data_parameter_widget.html b/forecastmanager/templates/forecastmanager/forecast_data_parameter_widget.html
new file mode 100644
index 0000000..d4268d6
--- /dev/null
+++ b/forecastmanager/templates/forecastmanager/forecast_data_parameter_widget.html
@@ -0,0 +1,11 @@
+<input type="{{ widget.type }}" name="{{ widget.name }}"{% if widget.value != None %}
+       value="{{ widget.value|stringformat:'s' }}"{% endif %}{% include "django/forms/widgets/attrs.html" %}
+       style="display: none">
+
+<select style="display: none" id="{{ widget.attrs.id }}_parameter_list">
+    <option value="">-----------</option>
+    {% for option in widget.parameter_list %}
+        <option value="{{ option.value }}"
+                {% if widget.value and widget.value == option.value %}selected{% endif %}>{{ option.label }}</option>
+    {% endfor %}
+</select>
\ No newline at end of file
diff --git a/forecastmanager/widgets.py b/forecastmanager/widgets.py
index a19b3ab..a4c5c6b 100644
--- a/forecastmanager/widgets.py
+++ b/forecastmanager/widgets.py
@@ -1,12 +1,12 @@
 import json
 
-from django.forms import widgets
+from django.forms import widgets, TextInput
 from django.templatetags.static import static
 from wagtail.telepath import register
 from wagtail.utils.widgets import WidgetWithScript
 from wagtail.widget_adapters import WidgetAdapter
 
-from forecastmanager.constants import WEATHER_CONDITION_ICONS
+from forecastmanager.constants import WEATHER_CONDITION_ICONS, WEATHER_PARAMETER_CHOICES
 
 
 class WeatherSymbolChooserWidget(WidgetWithScript, widgets.TextInput):
@@ -52,3 +52,40 @@ class Media:
 
 
 register(WeatherSymbolWidgetAdapter(), WeatherSymbolChooserWidget)
+
+
+class DataParameterWidget(WidgetWithScript, TextInput):
+    template_name = "forecastmanager/forecast_data_parameter_widget.html"
+
+    def __init__(self, attrs=None, **kwargs):
+        default_attrs = {}
+
+        if attrs:
+            default_attrs.update(attrs)
+
+        super().__init__(default_attrs)
+
+    def get_context(self, name, value, attrs):
+        context = super().get_context(name, value, attrs)
+
+        options = []
+
+        for choice in WEATHER_PARAMETER_CHOICES:
+            options.append({
+                "value": choice[0],
+                "label": choice[1],
+            })
+
+        context["widget"].update({
+            "parameter_list": options
+        })
+
+        return context
+
+    def render_js_init(self, id_, name, value):
+        return "new DataParameterWidget({0},{1});".format(json.dumps(id_), json.dumps(value))
+
+    class Media:
+        js = [
+            "forecastmanager/js/forecast-data-parameter-widget.js",
+        ]
diff --git a/setup.cfg b/setup.cfg
index 9538160..4460c12 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,6 +1,6 @@
 [metadata]
 name = forecastmanager
-version = 0.4.7
+version = 0.4.8
 description = Integration of Weather City Forecasts Manager in Wagtail Projects.
 long_description = file:README.md
 long_description_content_type = text/markdown