Details from the National Weather Service
* WHAT...Temperatures as low as 35 will result in frost formation. * WHERE...Portions of northern Indiana and northwest Ohio. * WHEN...From 1 AM EDT /midnight CDT/ to 9 AM EDT /8 AM CDT/ Monday. * IMPACTS...Frost could harm sensitive outdoor vegetation. Sensitive outdoor plants may be killed if left uncovered. Take steps now to protect tender plants from the cold.
The ground at the station reading just now
A sensor at the foot of the station mast measures the air 2 inches above the grass and the soil at 2, 4 and 8 inches deep, every 5 minutes. On clear, calm nights the grass cools faster than the air the station measures 5 feet up, so frost forms on the grass first; the soil gives back the heat it stored by day, more slowly the deeper you go. The grass probe was painted white and moved to its permanent mount on October 18, 2026; earlier grass readings are less reliable.
The grass is 17.0° colder than the air the station measures: the ground is losing heat to the sky faster than the air above it.
Snow on the ground
Bare. From the forecast models (no recent report).
The station's owner reports bare, patchy, covered or deep ground (and depth from snow stakes) when snow is around. Between reports the estimate is carried forward: new snow from the forecast models, melting from the station's own temperatures, settling. A report counts for less as it ages, and after ten days the models' snow depth takes over. A buried grass probe (one that stops following the sky, or sits at 32° while the air is well above freezing) also counts as snow on the ground.
The last 48 hours
Shaded bands are night (sunset to sunrise). The dashed line is the station's air, the dotted line its dew point, and the thin line at 32° marks freezing. Soil swings get smaller and later the deeper you go: the 8-inch soil barely notices one day's weather.
Night cooling last 24 hours
The grass got down to 29.5° at 6:50 AM, when the station's air was 31.6°. At most the grass ran 19.0° below the air (6:50 PM).
It was at or below freezing for 12 h, starting 9:10 PM. The grass reached the dew point, so frost formed.
Grass minus the station's air. Below zero (blue): the ground is losing heat to a clear sky faster than the air. Above zero (orange): sunshine is warming the ground. Big blue dips mean calm, clear nights, the ones our forecast finds hardest.
Soil profile now and 12 hours ago
Records since Oct 17, 2026 · 2 nights
Recent nights
| Night of | Grass low | Air low | Grass most below the air | At 32° or less |
|---|---|---|---|---|
| Sun Oct 18 (part) | 38.9° | 55.9° | 19.0° | - |
| Sat Oct 17 (part) | 29.5° | 31.5° | 11.9° | 12 h frost |
Soil extremes
| Depth | Coldest | Warmest | ||
|---|---|---|---|---|
| 2 in | 47.5° | Oct 18 | 54.0° | Oct 17 |
| 4 in | 50.7° | Oct 18 | 55.0° | Oct 17 |
| 8 in | 53.3° | Oct 18 | 56.5° | Oct 17 |
A night runs from noon to noon and is named for its evening. "(part)" marks a night with gaps in the readings, such as the night the sensor went in. "Frost" means the grass reached both 32° and the dew point, so ice actually formed. Readings taken while testing the probes are left out. The station's air records (all-time extremes, monthly climate) are on Station records.
Sensor health
The sensor wakes every 5 minutes, reads its four probes and radios them about 500 feet to a small receiver in the house. The battery chart is by hour: a single lithium cell reads about 4.2 V full and should be recharged below about 3.5 V. Radio signal is in dBm (closer to zero is stronger); the margin is how far the signal sits above the background noise. The station computer sends an alert if readings stop or the battery runs low.