textproduct: Medford

KEY MESSAGES

* Cool overnight temperatures may reach frost conditions on early Wednesday morning.

* Widespread rainfall is expected on Wednesday, with gusty winds expected along the coast, into the Shasta Valley, and across the east side.

* Rainfall looks to continue but decrease on Thursday, with showers becoming more intermittent towards the end of the week. Cool early morning temperatures may return east of the Cascades as well.

DISCUSSION

Warm and dry weather continues this afternoon across northern California and southern Oregon. Southerly flow around an approaching cutoff low is expected to bring elevated breezes t most areas this afternoon. Wind gusts of 35 to 40 mph are already bring observed in the Shasta Valley and over terrain east of the Cascades. These gusty winds and ongoing dry conditions are addressed by a Red Flag Warning for critical fire weather conditions. Even in areas outside of the Warning, dry and breezy conditions can still bring rapid fire growth. Please be aware of any activity that can create sparks or ignite a fire.

The cutoff low will move over the area on Tuesday, dropping daytime highs by 5 to 15 degrees. Gusty winds return to the Shasta Valley and across the east side, but rising relative humidities are preventing critical fire weather conditions. Moisture moving with this low looks to bring slight chances for light precipitation to coastal areas, western Siskiyou County, and along the Cascades on Tuesday afternoon and evening. 10-20% thunderstorm chances are present for the Siskiyous and Cascades in this time frame, suggesting that rain showers may be a component of any thunderstorms that do develop. Farther east, the cooler air bring by the cutoff may reach frost conditions early Wednesday morning for some areas east of the Cascades. Increased humidity and overnight cloud cover may be enough insulation to prevent those temperatures, so confidence in frost conditions occuring is moderate. Please see NPWMFR for a complete list of communities that may be affected.

On Wednesday, a cold front attached to an approaching low pressure system will bring temperatures 10 to 20 degrees below normal for most areas. The front's approach will bring gusty winds to coastal cities, into the Shasta Valley, and to most east side areas. Areas west of the Cascades will see rainfall, with 1.5 to 2.5 inches forecast for Curry COunty. Coos and northern Douglas counties as well as the Illinois Valley could see up to an inch of rain. The Umpqua and Klamath River Valleys are forecast to see around half an inch. Other west side areas look to be in the 0.1 to 0.3 inch range. Lake and southern Klamath counties could see up to 0.1 inches, while Modoc will only see a few hundreths of an inch at most for Wednesday.

While rainfall amounts are not hazardous, the first rain after a dry period can bring local hazards. Areas around burn scars may see additional water runoff or debris flows. For travel along highways 42, 38, and 138 as well as around the East Evans Creek and Fielder Mountain or any other burn scars in the area, this is a concern. Additionally, rainfall can locally accumulate in areas with poor or blocked drainage. Rainfall can also lift oils on roads accumulated through summer months to the surface and create slick conditions. In some areas, rainfall may be enough to impair visibility. Please take extra care if traveling is necessary on Wednesday.

For Thursday and beyond, the low pressure draws closer then lingers in the area. The low's approach will help widespread showers continue into Thursday. Southwest flow around the low looks to help light showers reach Modoc and east Lake counties. For Friday and the weekend, rainfall becomes more intermittent. With skies clearing somewhat, frost concerns may return on early Saturday and Sunday mornings, but that is hard to say with significant confidence this far out. -TAD

AVIATION (18Z TAFs)

While clear at North Bend now, we are expecting a stratus layer to redevelop bringing IFR to MVFR conditions today/tonight. Additionally, some light rain or drizzle may be possible along the coast tonight. Inland sites will have plenty of sunshine today and typical diurnal breezes. Some high clouds may develop today, but overall VFR conditions will prevail for inland terminals.

-Guerrero

MARINE...Updated 230 PM PDT Sunday, August 31, 2026

While breezy southerly winds continue over area waters, seas have fallen below advisory levels. A cold front will move through the area late Tuesday night into Wednesday bringing gusty southerly gales and steep to very steep seas. Winds ease on Thursday but westerly swell may support continuing unsettled seas into the end of the week.

FIRE WEATHER...Updated 1200 PM PDT Monday, August 31, 2026

Red Flag Warning remains in effect until 8pm today for strong winds and low RH.

Tomorrow, gusty winds will again reach critical levels for parts of the forecast area, but humidities will be slightly above thresholds as temperatures trend cooler. In other words, not expecting critical fire weather conditions to be met starting tomorrow and continuing through the rest of the week. Through this stretch of fall-like weather, there will also be chances for light showers, especially the Wed-Thurs timeframe where we have the highest chances and highest rainfall amounts. That said, there is also a 10%-20% probability of thunderstorms Tuesday afternoon, mainly for areas near west-central Siskiyou County, but more widespread in coverage on Thursday with slightly higher chances around 10%-30%. However, not expecting these lightning chances to warrant any fire weather concerns/warnings.

MFR WATCHES/WARNINGS/ADVISORIES

OR...Red Flag Warning until 8 PM PDT this evening for ORZ624.

Frost Advisory from 4 AM to 8 AM PDT Wednesday for ORZ029>031.

CA...Red Flag Warning until 8 PM PDT this evening for CAZ280-281-284- 285.

Frost Advisory from 4 AM to 8 AM PDT Wednesday for CAZ085.

PACIFIC COASTAL WATERS...Gale Watch from late Tuesday night through Wednesday afternoon for PZZ350-356-370-376.