Thank you, Theresa, for your question!
  Using a metal thermometer insert it into the soil at the depth your seed packet stated to plant your seeds, (usually 3-4 inches). Take the temperature early in the morning as your soil may warm later in the day. Do this for a few days to get a consistent idea of the temperature you are measuring. Consult with a weather platform to view if any cold snaps are predicted and adjust your planting accordingly or cover your seeds with a thick mulch.
  Most garden centers will sell a soil thermometer around $10.00, or you can use a meat thermometer provided it will measure the range you want to measure. 
  Good seed germination is dependent upon soil temperature (not air temperature), soil moisture and sunlight. With that in mind I have included two articles to assist in determining the different soil temperatures for various vegetable seeds.
Soil temperature conditions for vegetable seed germination | OSU Extension Service (oregonstate.edu)

Determine soil temperatures before planting vegetables for improved results - MSU Extension
May you enjoy a great gardening season!