However you protect your sensitive outdoor plants, the time has arrived.

The National Weather Service has issued the first frost advisory of the season for the Lincoln area from 4 a.m. to 9 a.m. Tuesday.

A cold high pressure system is expected to move south into the region overnight. Clear skies and light winds will provide favorable conditions for areas of frost as surface temperatures are forecast to drop into the lower to mid 30s overnight. Low-lying areas will be most susceptible to frost, the weather service said.

A frost advisory means that frost is possible. Sensitive outdoor plants may be killed if left uncovered.

The frost advisory covers most of eastern Nebraska. Further west, including the Grand Island and Kearney areas, a freeze warning has been issued. In those areas, overnight lows are predicted to drop into the 29- to 32-degree range.

 Typically, across eastern Nebraska, the weather service said, the first fall frost occurs from the third week of September into the first week of October.  The first fall freeze occurs late in September or in the first week or two of October.  A hard freeze — 28 degrees or colder — typically occurs around the third week of October, but varies significantly from site to site.

Tuesday’s morning’s low in Lincoln is expected to be the coldest of the week.

Last year, Lincoln’s first frost showed up Oct. 22; its first freeze on Oct. 23 and its first hard freeze Oct. 28.

Lincoln’s high temperature is expected is the mid-60s, with a 40 percent chance of more rain. About 0.8 of an inch of rain fell Monday morning in the Capital City.