If the temperatures will stay above 50 degrees, it should be safe to transplant the seedlings. 

A general rule of thumb, when using air temperatures as a guide, is to wait until night time temperatures are steadily at or above 50° Fahrenheit before transplanting peppers, tomatoes, and most tender seedlings into the ground.

The best way to determine whether it’s time to transplant seedlings is to use a soil thermometer, which you can find inexpensively in a nursery or hardware store. The ideal soil temperature for planting and growing most vegetables is 65° to 75°F.

Wait if you can for a gloomy, cloudy day to plant seedlings in the garden.

For more information on transplanting seedlings, see

https://extension.oregonstate.edu/sites/default/files/documents/12281/early-seasonvegetables.pdf

https://extension.umn.edu/planting-and-growing-guides/planting-vegetable-garden#starting-seeds-1975410