Johnson County, WY

Alerts

Warning Area

County Line

Alerts are listed in order of start time and level of severity. Click on the alert title to read details for each alert.

In effect from Monday 04/20 11:00 AM MDT – Monday 04/20 8:00 PM MDT

Issued by NWS Riverton WY

* AFFECTED AREA: In Central WY...Fire Weather Zones 280 and 289.

* COUNTIES AFFECTED: In Central WY...Fremont...Natrona. In Southwest WY...Sweetwater.

* IMPACTS: Low Humidities and Strong Gusty Winds could cause erratic fire behavior.

* WIND: West 10 to 20 mph with gusts of 30 to 35 mph.

* HUMIDITY: As low as 9 percent.

What to do

A Red Flag Warning means that critical fire weather conditions are either occurring now....or will shortly. A combination of strong winds...low relative humidity...and warm temperatures can contribute to extreme fire behavior.

Areas impacted

Natrona County/Casper BLM
Granite/Green/Ferris/Rattlesnake Mountains

No alerts for Johnson County, WY, on Tuesday

No alerts for Johnson County, WY, on Wednesday

No alerts for Johnson County, WY, on Thursday

No alerts for Johnson County, WY, on Friday

Briefing

Last updated:

Monday, Apr 20, 2026, 5:30 AM

Download briefing [pdf]

From the forecaster

Monday's Weather Story

Created by the NWS Riverton WFO

Today’s forecast is warm and breezy. This warm, dry, and breezy weather gives way for elevated to critical fire weather conditions, especially for Natrona County and southeast Fremont County.

Riverton Area Forecast Discussion

Seven-day weather risk overview

Daily weather risk summary

	Mon 4/20	Tue 4/21	Wed 4/22	Thu 4/23	Fri 4/24	Sat 4/25	Sun 4/26
risk level	out of 10	out of 10	out of 10	out of 10	out of 10	out of 10	out of 10

No risk

Low risk

High risk

See the detailed risk analysis

Weather forecasting office

Riverton Forecast Office