Report

Space weather: solar flux 105, 10 below its 90-day average of 115. Maximum usable frequency 18 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 5.7 megahertz, so 80 meters is good for NVIS, 60 meters marginal. K index 1, very quiet. 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 7:07 AM, sunset 6:50 PM, day length 11 hours 43 minutes. Moonset 2:56 PM at 304 degrees, west northwest. No moonrise today. Last quarter moon, 44 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 8:07 AM, 76 degrees high and 3 percent closer than average, a good time to listen for EME signals on 2 meters and up.

VHF and UHF tropospheric enhancement is often strongest from sunset to early morning, when a nighttime temperature inversion forms.

Amateur satellite passes for the next four hours. AO7, linear transponder: at 8:12 PM rising in the south southwest, 31 degrees. SO 50, FM: at 8:20 PM rising in the north northwest, 44 degrees. PO 101, FM, on a schedule: at 8:31 PM rising in the north northeast, 87 degrees, overhead. AO 91, FM: at 9:35 PM rising in the north northeast, 41 degrees. For the next pass, SO 50: uplink 145.85 megahertz with a 67 hertz tone, downlink 436.795. Send a 74.4 hertz tone briefly first to start its timer. Frequencies and live status at amsat.org/status. Pass predictions at n2yo.com.

Satellite tip: a small dual-band handheld Yagi is all you need for the FM satellites.

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 3 hours ago: No ducting strong enough for amateur VHF or UHF bands over Oakland. K6EEG's experimental tropo forecast, based on NOAA atmospheric model data, for the next 12 hours. Bay Area coast, peaking around 4 AM: ducting expected on 70 centimeters, 85 percent; a chance of ducting on 2 meters, 45 percent. Southern California coast: ducting likely on 70 centimeters, 75 percent; a slight chance of ducting on 2 meters, 25 percent. Nothing toward Hawaii.

Events. The California QSO Party, now under way, California stations in demand. IARU Region 1UHF/Microwaves Contest, now under way. IARU Region 2 Area GHFSSB Contest, now under way.

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.

Keep your FCC license information current in the ULS, including your email address. The FCC sends license notices by email. Many handhelds can receive NOAA Weather Radio. Program the local channels.

Current weather conditions at San Francisco International Airport: Clear. Temperature 79 degrees Fahrenheit. Dew point 54 degrees Fahrenheit. Relative humidity 42 percent. Wind calm. Barometric pressure 29.79 inches of mercury, low pressure. Visibility 10 miles.

National Weather Service forecast. Tonight: Mostly clear, with a low around 62. West wind 0 to 9 miles per hour. Sunday: Partly sunny. High near 83, with temperatures falling to around 75 in the afternoon. Northwest wind 1 to 10 miles per hour. Sunday Night: Mostly clear, with a low around 61. West southwest wind 2 to 9 miles per hour.

Tide predictions for today at the San Francisco Embarcadero gauge. High tide at 7:11 AM, 4.4 feet. Low tide at 11:12 AM, 3.5 feet. High tide at 5:11 PM, 5.8 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 9 seconds, from the south southwest. Wind at the buoy 12 knots from the west northwest. Ocean water temperature 61 degrees Fahrenheit. San Francisco Bay water temperature 67 degrees Fahrenheit. Golden Gate currents: maximum ebb 3.3 knots at 9:40 PM, then slack water at 3:01 AM, then maximum flood 1.9 knots at 5:40 AM.

Air quality for field operations, from the Bay Area Air District's San Francisco Arkansas Street monitoring station. Fine particulate matter, PM2.5, is 3 micrograms per cubic meter, rated good. Ozone is 36 parts per billion. Nitrogen dioxide is 7 parts per billion. For more information visit the Bay Area Air District or openaq.org on the web.

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 2.9, near South Lake Tahoe. 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.