diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3aa6a62..f9cb5ad 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+1.0.1 (03/07/2026) - Add YARD doc comments to all public classes and methods. Expand README with polygon, error handling, and client usage examples. Handle malformed JSON responses (raise `HttpError` instead of `JSON::ParserError`). Handle missing time fields in alert data (return `nil` instead of raising `TypeError`).
+
+***
+
 1.0.0 (03/07/2026) - Major rewrite: migrate from defunct `alerts.weather.gov` XML feed to `api.weather.gov/alerts` JSON API. Drop all runtime dependencies (`httpclient`, `nokogiri`) in favor of Ruby stdlib (`net/http`, `json`). Require Ruby >= 3.1. Add `area` option for state-based filtering. Replace Travis CI with GitHub Actions. Add RuboCop. **Breaking:** remove `url` option (use `area` instead), remove `Polygon#image_url`, remove `strict` option.
 
 ***
diff --git a/README.md b/README.md
index 7c85de2..eb30f97 100644
--- a/README.md
+++ b/README.md
@@ -36,7 +36,7 @@ alert.effective_at
 alert.expires_at
 alert.published_at
 alert.area
-alert.polygon
+alert.polygon           # Gull::Polygon or nil
 alert.geocode.fips6
 alert.geocode.ugc
 alert.urgency
@@ -51,8 +51,47 @@ To get alerts for a single state or territory, pass the area option:
 alerts = Gull::Alert.fetch(area: 'OK')
 ```
 
-##Notes, Caveats
-This library fetches active alerts from the [NWS API](https://api.weather.gov) (`api.weather.gov/alerts/active`), which returns GeoJSON. No authentication is required but the API does require a `User-Agent` header (set automatically by the gem).
+### Polygons
+
+Alerts with geographic boundaries include a `Polygon` object:
+
+```ruby
+alert.polygon.coordinates
+# => [[34.57, -97.56], [34.77, -97.38], ...]
+
+alert.polygon.to_s
+# => "34.57,-97.56 34.77,-97.38 ..."
+
+alert.polygon.to_wkt
+# => "POLYGON((-97.56 34.57, -97.38 34.77, ...))"
+```
+
+### Error Handling
+
+```ruby
+begin
+  alerts = Gull::Alert.fetch
+rescue Gull::TimeoutError => e
+  # request timed out
+rescue Gull::HttpError => e
+  # non-success response or connection failure
+  e.original # wrapped exception, if any
+end
+```
+
+### Advanced: Client
+
+For direct access to unparseable features, use `Client`:
+
+```ruby
+client = Gull::Client.new(area: 'OK')
+alerts = client.fetch
+client.errors # features that could not be parsed
+```
+
+## Notes, Caveats
+
+This library fetches active alerts from the [NWS API](https://api.weather.gov) (`api.weather.gov/alerts/active`), which returns GeoJSON. No authentication is required but the API does require a `User-Agent` header (set automatically by the gem). See the [NWS API docs](https://www.weather.gov/documentation/services-web-api) for more details.
 
 The NWS will often cancel or update alerts before their expiration time. The API only returns currently active alerts.
 
diff --git a/lib/gull/alert.rb b/lib/gull/alert.rb
index 03eb7db..9fa28de 100644
--- a/lib/gull/alert.rb
+++ b/lib/gull/alert.rb
@@ -1,7 +1,26 @@
 # frozen_string_literal: true
 
 module Gull
+  # Represents a single NWS weather alert (warning, watch, or
+  # advisory). Use +Alert.fetch+ to retrieve active alerts from the
+  # NWS API.
   class Alert
+    # @!attribute id [rw] NWS alert identifier
+    # @!attribute title [rw] Alert headline
+    # @!attribute summary [rw] Full alert description text
+    # @!attribute link [rw] Canonical URL for this alert
+    # @!attribute alert_type [rw] Event type (e.g. "Tornado Warning")
+    # @!attribute polygon [rw] Alert area as a Polygon, or nil
+    # @!attribute area [rw] Human-readable area description
+    # @!attribute effective_at [rw] Time the alert takes effect
+    # @!attribute expires_at [rw] Time the alert expires
+    # @!attribute updated_at [rw] Onset time, or sent time if absent
+    # @!attribute published_at [rw] Time the alert was sent
+    # @!attribute urgency [rw] Urgency level as a Symbol
+    # @!attribute severity [rw] Severity level as a Symbol
+    # @!attribute certainty [rw] Certainty level as a Symbol
+    # @!attribute geocode [rw] Geocode with UGC and FIPS codes
+    # @!attribute vtec [rw] VTEC string, or nil
     attr_accessor :id, :title, :summary, :link, :alert_type, :polygon,
                   :area, :effective_at, :expires_at, :updated_at,
                   :published_at, :urgency, :severity, :certainty,
@@ -11,11 +30,13 @@ def initialize
       self.geocode = Geocode.new
     end
 
+    # Fetches active alerts from the NWS API.
     def self.fetch(options = {})
       client = Client.new(options)
       client.fetch
     end
 
+    # Populates this alert from a GeoJSON feature hash.
     def parse(feature)
       props = feature['properties']
       parse_core_attributes(feature, props)
@@ -38,10 +59,14 @@ def parse_core_attributes(feature, props)
     end
 
     def parse_times(props)
-      self.effective_at = Time.parse(props['effective'])
-      self.expires_at = Time.parse(props['expires'])
-      self.published_at = Time.parse(props['sent'])
-      self.updated_at = Time.parse(props['onset'] || props['sent'])
+      self.effective_at = parse_time(props['effective'])
+      self.expires_at = parse_time(props['expires'])
+      self.published_at = parse_time(props['sent'])
+      self.updated_at = parse_time(props['onset'] || props['sent'])
+    end
+
+    def parse_time(value)
+      value ? Time.parse(value) : nil
     end
 
     def parse_categories(props)
diff --git a/lib/gull/client.rb b/lib/gull/client.rb
index 05da280..5e75be5 100644
--- a/lib/gull/client.rb
+++ b/lib/gull/client.rb
@@ -1,21 +1,28 @@
 # frozen_string_literal: true
 
 module Gull
+  # Low-level HTTP client for the NWS alerts API. Handles
+  # fetching, parsing, and error wrapping. Most callers should
+  # use +Alert.fetch+ instead.
   class Client
     URL = 'https://api.weather.gov/alerts/active'
     USER_AGENT = "gull/#{VERSION} (Ruby #{RUBY_VERSION})".freeze
 
+    # Features that could not be parsed are collected here.
     attr_accessor :errors
 
     def initialize(options = {})
       @options = options
     end
 
+    # Fetches active alerts and returns an Array of Alert objects.
     def fetch
       self.errors = []
       json = response
       data = JSON.parse(json)
       process(data['features'] || [])
+    rescue JSON::ParserError
+      raise HttpError, 'Unexpected response from NWS API'
     end
 
     private
diff --git a/lib/gull/error.rb b/lib/gull/error.rb
index 55daf7a..1e0b3cd 100644
--- a/lib/gull/error.rb
+++ b/lib/gull/error.rb
@@ -3,6 +3,8 @@
 require 'English'
 
 module Gull
+  # Raised when the NWS API returns a non-success response or the
+  # connection fails. Wraps the original exception, if any.
   class HttpError < StandardError
     attr_reader :original
 
@@ -12,6 +14,7 @@ def initialize(message, original = $ERROR_INFO)
     end
   end
 
+  # Raised when the NWS API request times out.
   class TimeoutError < HttpError
   end
 end
diff --git a/lib/gull/geocode.rb b/lib/gull/geocode.rb
index c2c99d4..01b3ac9 100644
--- a/lib/gull/geocode.rb
+++ b/lib/gull/geocode.rb
@@ -1,7 +1,10 @@
 # frozen_string_literal: true
 
 module Gull
+  # Holds UGC zone codes and FIPS county codes for an alert area.
   class Geocode
+    # @!attribute fips6 [rw] Space-separated FIPS 6 codes
+    # @!attribute ugc [rw] Space-separated UGC zone codes
     attr_accessor :fips6, :ugc
   end
 end
diff --git a/lib/gull/polygon.rb b/lib/gull/polygon.rb
index a9c0f31..e8073ad 100644
--- a/lib/gull/polygon.rb
+++ b/lib/gull/polygon.rb
@@ -1,17 +1,24 @@
 # frozen_string_literal: true
 
 module Gull
+  # Represents the geographic boundary of an alert as a series of
+  # lat/lon coordinate pairs. Coordinates are stored in [lat, lon]
+  # order.
   class Polygon
     attr_accessor :coordinates
 
+    # Accepts GeoJSON coordinates ([lon, lat]) and stores them as
+    # [lat, lon].
     def initialize(coords)
       self.coordinates = coords.map { |point| [point[1], point[0]] }
     end
 
+    # Returns coordinates as "lat,lon lat,lon ..." string.
     def to_s
       coordinates.map { |pair| pair.join(',') }.join(' ')
     end
 
+    # Returns coordinates in Well-Known Text format.
     def to_wkt
       pairs = coordinates.map { |pair| "#{pair.last} #{pair.first}" }
                          .join(', ')
diff --git a/lib/gull/version.rb b/lib/gull/version.rb
index 45388c4..4ca2468 100644
--- a/lib/gull/version.rb
+++ b/lib/gull/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module Gull
-  VERSION = '1.0.0'
+  VERSION = '1.0.1'
 end
diff --git a/spec/alert_spec.rb b/spec/alert_spec.rb
index f17ef89..5861a25 100644
--- a/spec/alert_spec.rb
+++ b/spec/alert_spec.rb
@@ -154,6 +154,18 @@ def stub_alerts(json)
     expect(alerts.size).to eq(0)
   end
 
+  it 'should handle missing onset time' do
+    feature = load_feature('missing_times.json')
+    stub_alerts(wrap_features(feature))
+
+    alert = Gull::Alert.fetch.first
+
+    expect(alert.effective_at).to be_nil
+    expect(alert.expires_at).to eq Time.parse('2026-03-07T08:15:00-06:00')
+    expect(alert.updated_at).to eq Time.parse('2026-03-07T07:48:00-06:00')
+    expect(alert.published_at).to eq Time.parse('2026-03-07T07:48:00-06:00')
+  end
+
   it 'should handle missing event' do
     json = File.read 'spec/fixtures/missing_event.json'
     stub_alerts(json)
diff --git a/spec/client_spec.rb b/spec/client_spec.rb
index f116be6..1abc00b 100644
--- a/spec/client_spec.rb
+++ b/spec/client_spec.rb
@@ -71,6 +71,18 @@
     end
   end
 
+  it 'should raise error on malformed JSON response' do
+    stub_request(:get, 'https://api.weather.gov/alerts/active')
+      .to_return(status: 200, body: '<html>Bad Gateway</html>',
+                 headers: {})
+
+    client = Gull::Client.new
+    expect { client.fetch }
+      .to raise_error(Gull::HttpError, /Unexpected response/) do |e|
+        expect(e.original).to be_a(JSON::ParserError)
+      end
+  end
+
   it 'should filter by area' do
     json = File.read 'spec/fixtures/alerts.json'
 
diff --git a/spec/fixtures/features/missing_times.json b/spec/fixtures/features/missing_times.json
new file mode 100644
index 0000000..991de83
--- /dev/null
+++ b/spec/fixtures/features/missing_times.json
@@ -0,0 +1,36 @@
+{
+  "id": "https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.missing-times-test",
+  "type": "Feature",
+  "geometry": null,
+  "properties": {
+    "@id": "https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.missing-times-test",
+    "@type": "wx:Alert",
+    "id": "urn:oid:2.49.0.1.840.0.missing-times-test",
+    "areaDesc": "Test County",
+    "geocode": {
+      "SAME": ["005001"],
+      "UGC": ["ARZ001"]
+    },
+    "affectedZones": [],
+    "references": [],
+    "sent": "2026-03-07T07:48:00-06:00",
+    "effective": null,
+    "onset": null,
+    "expires": "2026-03-07T08:15:00-06:00",
+    "ends": null,
+    "status": "Actual",
+    "messageType": "Alert",
+    "category": "Met",
+    "severity": "Moderate",
+    "certainty": "Likely",
+    "urgency": "Expected",
+    "event": "Special Weather Statement",
+    "sender": "w-nws.webmaster@noaa.gov",
+    "senderName": "NWS Test",
+    "headline": "Test alert with missing onset",
+    "description": "Test description.",
+    "instruction": null,
+    "response": "Monitor",
+    "parameters": {}
+  }
+}