[GENERAL] Syntax error needs fresh eyeballs

   My schema includes three tables and psql throws an error I'm not seeing
when I try to read the schema into the database. I'd appreciate fresh eyes
looking at the table and learning what error I'm not seeing.

   The tables:

CREATE TABLE Weather (
   site_id INTEGER PRIMARY KEY,
   site_name TEXT,
   site_location TEXT
);


CREATE TABLE Weather_Params (
   site_id INTEGER
     REFERENCES Weather(site_id),
   param TEXT,
   param_unit TEXT,
   freq INTEGER,
   freq_unit TEXT,
   equip TEXT,
   PRIMARY KEY (site_id, param)
);


CREATE TABLE Weather_Data (
   site_id INTEGER
     REFERENCES Weather(site_id),
   monit_date DATE,
   monit_time TIME,
   read_by TEXT,  -- name of employee collecting data
   param TEXT
     REFERENCES Weather_Params(param),
   param_value REAL,
   PRIMARY KEY (site_id, monit_date, monit_time, param)
);

   The error:

ERROR:  there is no unique constraint matching given keys for referenced
table "weather_params".

TIA,

Rich