diff --git a/watttime/api.py b/watttime/api.py
index bc5b18c..4b4c399 100644
--- a/watttime/api.py
+++ b/watttime/api.py
@@ -24,6 +24,7 @@ def __init__(self, username: Optional[str] = None, password: Optional[str] = Non
         """
         self.username = username or os.getenv("WATTTIME_USER")
         self.password = password or os.getenv("WATTTIME_PASSWORD")
+        self.certificate_location = os.getenv("PEM_CERTIFICATE")
         self.token = None
         self.token_valid_until = None
 
@@ -39,6 +40,7 @@ def _login(self):
         rsp = requests.get(
             url,
             auth=requests.auth.HTTPBasicAuth(self.username, self.password),
+            verify=self.certificate_location,
             timeout=20,
         )
         rsp.raise_for_status()
@@ -126,7 +128,7 @@ def register(self, email: str, organization: Optional[str] = None) -> None:
             "org": organization,
         }
 
-        rsp = requests.post(url, json=params, timeout=20)
+        rsp = requests.post(url, json=params, verify=self.certificate_location, timeout=20)
         rsp.raise_for_status()
         print(
             f"Successfully registered {self.username}, please check {email} for a verification email"
@@ -163,7 +165,7 @@ def region_from_loc(
             "longitude": str(longitude),
             "signal_type": signal_type,
         }
-        rsp = requests.get(url, headers=headers, params=params)
+        rsp = requests.get(url, headers=headers, params=params, verify=self.certificate_location)
         if not rsp.ok:
             if rsp.status_code == 404:
                 # here we specifically cannot find a location that was provided
@@ -219,7 +221,7 @@ def get_historical_jsons(
 
         for c in chunks:
             params["start"], params["end"] = c
-            rsp = requests.get(url, headers=headers, params=params)
+            rsp = requests.get(url, headers=headers, params=params, verify=self.certificate_location)
             try:
                 rsp.raise_for_status()
                 j = rsp.json()
@@ -325,7 +327,7 @@ def get_access_json(self) -> Dict:
             self._login()
         url = "{}/v3/my-access".format(self.url_base)
         headers = {"Authorization": "Bearer " + self.token}
-        rsp = requests.get(url, headers=headers)
+        rsp = requests.get(url, headers=headers, verify=self.certificate_location)
         rsp.raise_for_status()
         return rsp.json()
 
@@ -409,7 +411,7 @@ def get_forecast_json(
 
         url = "{}/v3/forecast".format(self.url_base)
         headers = {"Authorization": "Bearer " + self.token}
-        rsp = requests.get(url, headers=headers, params=params)
+        rsp = requests.get(url, headers=headers, params=params, verify=self.certificate_location)
         rsp.raise_for_status()
         return rsp.json()
 
@@ -488,7 +490,7 @@ def get_historical_forecast_json(
 
         for c in chunks:
             params["start"], params["end"] = c
-            rsp = requests.get(url, headers=headers, params=params)
+            rsp = requests.get(url, headers=headers, params=params, verify=self.certificate_location)
             try:
                 rsp.raise_for_status()
                 j = rsp.json()
@@ -565,6 +567,6 @@ def get_maps_json(
         url = "{}/v3/maps".format(self.url_base)
         headers = {"Authorization": "Bearer " + self.token}
         params = {"signal_type": signal_type}
-        rsp = requests.get(url, headers=headers, params=params)
+        rsp = requests.get(url, headers=headers, params=params, verify=self.certificate_location)
         rsp.raise_for_status()
         return rsp.json()