Report

Space weather: solar flux 105, 10 below its 90-day average of 115. Maximum usable frequency 19 megahertz, measured by the Idaho Falls ionosonde via KC2G: long-distance paths open through 20 meters, 17 meters marginal, 15 meters and up closed. Critical frequency 6.1 megahertz, so 80 and 60 meters are good for NVIS. Daytime absorption limits 160 and 80 meters to short range. K index 4, minor geomagnetic storm. No significant flares. Data from NOAA.

We're in the declining phase of Solar Cycle 25, which peaked in October 2024. Sunspots and solar flux are trending down toward the next minimum, expected around 2030.

Sun and moon, Pacific Daylight Time: sunrise 7:08 AM, sunset 6:48 PM, day length 11 hours 40 minutes. Moonrise 12:27 AM at 58 degrees, east northeast; moonset 3:40 PM at 299 degrees, west northwest. Waning crescent, 35 percent lit. The Orionid meteor shower peaks Wednesday, October 21, a meteor scatter opportunity on 6 and 2 meters. Moonbounce: the moon peaks tomorrow at 9:02 AM, 71 degrees high and 3 percent closer than average, a good time to listen for EME signals on 2 meters and up.

After sunrise the D layer builds, and 160 and 80 meters go quiet on daytime paths within an hour or two.

Amateur satellite passes for the next four hours. The ISS, FM crossband repeater, when active: at 5 PM rising in the northwest, 50 degrees. RS 44, linear transponder, SSB and CW: at 5:06 PM rising in the south southeast, 35 degrees. For the next pass, the ISS: uplink 145.99 megahertz with a 67 hertz tone, downlink 437.8. Frequencies and live status at amsat.org/status. Pass predictions at n2yo.com.

Satellite tip: work full duplex if you can, listening to your own downlink, so you don't transmit over others.

DX activity, via the cluster network and hamqsl.com. None spotted by West Coast stations right now. No aurora or 6 meter E-skip.

Tropospheric ducting, from balloon soundings 9 hours ago: over Oakland, a duct at 800 to 1100 feet, good for 33 centimeters and up. No matching ducts along the coast or toward Hawaii, so the enhancement is likely local. K6EEG's experimental tropo forecast, based on NOAA atmospheric model data, for the next 12 hours. Bay Area coast, peaking around 10 PM: ducting expected on 70 centimeters, 90 percent; ducting likely on 2 meters, 60 percent. Southern California coast: a chance of ducting on 70 centimeters, 30 percent. Nothing toward Hawaii.

Tropo openings favor horizontal antennas. For CW, try 144.05 to 144.1 megahertz on 2 meters, and 432.1 on 70 centimeters.

Events. The California QSO Party, now under way, California stations in demand. IARU Region 1UHF/Microwaves Contest, today. VHF-UHF FT8 Activity Contest, on Wednesday.

Club and community announcements. The SF Amateur Radio Club meets on the third Friday of each month, 7 PM at the Randall Museum. Visit sfarc.org for more details.

Check into a local net this week. Regular net practice is what makes emergency nets work.

Current weather conditions at San Francisco International Airport: Temperature 82 degrees Fahrenheit. Dew point 55 degrees Fahrenheit. Relative humidity 40 percent. Wind calm. Barometric pressure 29.86 inches of mercury, normal. Visibility 10 miles.

Batteries and radios in parked cars degrade in heat. Keep go-kit batteries somewhere cool.

National Weather Service forecast. This Afternoon: Partly sunny. High near 89, with temperatures falling to around 80 in the afternoon. West wind 3 to 10 miles per hour. Tonight: Mostly clear, with a low around 61. West southwest wind 0 to 9 miles per hour. Monday: Sunny. High near 81, with temperatures falling to around 75 in the afternoon. West northwest wind 0 to 10 miles per hour.

Tide predictions for today at the San Francisco Embarcadero gauge. Low tide at 12:34 AM, minus 0.1 feet. High tide at 8:16 AM, 4.7 feet. Low tide at 12:48 PM, 3.3 feet. High tide at 6:32 PM, 5.6 feet.

Ocean and bay conditions. No marine advisories in effect. From the San Francisco buoy, 18 nautical miles west of the Golden Gate: significant wave height 3 feet, slight seas, dominant period 8 seconds, from the west northwest. Wind at the buoy 8 knots from the west northwest. Ocean water temperature 60 degrees Fahrenheit. San Francisco Bay water temperature 66 degrees Fahrenheit. Golden Gate currents: slack water at 2:32 PM, then maximum flood 1.3 knots at 4:58 PM, then slack water at 6:58 PM.

Air quality for field operations, from the Bay Area Air District's San Francisco Arkansas Street monitoring station. Fine particulate matter, PM2.5, is 11 micrograms per cubic meter, rated good. Ozone is 50 parts per billion. Nitrogen dioxide is 8 parts per billion. For more information visit the Bay Area Air District or openaq.org on the web.

Sign up for your county's emergency alerts, such as Alert SF in San Francisco. Hams are often among the first to relay that information.

Seismic awareness for emergency communicators: no Bay Area earthquakes of magnitude 2.5 or greater in the past 24 hours. Largest in California in the past 24 hours: magnitude 2.3, near Coalinga. No earthquakes of magnitude 6 or greater worldwide. Seismic data from earthquake.usgs.gov.

Repeater sites can go off the air after a major earthquake. Program simplex frequencies and know your local simplex plan.