Report

Space weather: solar flux 105, 10 below its 90-day average of 115. Maximum usable frequency 7 megahertz, measured by the Idaho Falls ionosonde via KC2G: long-distance paths limited to the low bands, 40 meters marginal, 30 meters and up closed. Critical frequency 2.8 megahertz, too low for NVIS right now. K index 5, minor geomagnetic storm. No significant flares. Data from NOAA.

Geomagnetic storms can open aurora on 6 and 2 meters. Point north and listen for raspy, buzzy signals. 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, 39 percent lit. The Orionid meteor shower peaks Wednesday, October 21, a meteor scatter opportunity on 6 and 2 meters. Moonbounce: the moon peaks today 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.

After sunset the D layer fades, and 160, 80, and 40 meters open for long distance contacts, while 15 through 10 meters close as the F layer weakens.

Amateur satellite passes for the next four hours. FO 29, linear transponder, on a schedule: at 7:03 AM rising in the south southeast, 88 degrees, overhead. PO 101, FM, on a schedule: at 7:15 AM rising in the south southeast, 45 degrees. AO7, linear transponder: at 8:14 AM rising in the north northeast, 86 degrees, overhead. AO 91, FM: at 9:49 AM rising in the south, 33 degrees. For the next pass, FO 29: inverting linear transponder, uplink near 145.95 megahertz lower sideband, downlink near 435.85 upper sideband. Frequencies and live status at amsat.org/status. Pass predictions at n2yo.com.

Satellite tip: rotate a handheld Yagi as the satellite passes to follow its changing polarization. A small twist can bring back a fading signal.

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 14 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 5 PM: ducting likely on 70 centimeters, 60 percent; a slight chance of ducting on 2 meters, 15 percent. Southern California coast, peaking around 2 PM: ducting expected on 70 centimeters, 80 percent; a chance of ducting on 2 meters, 40 percent. Nothing toward Hawaii.

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.

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: All values in SI units. Temperature 18 degrees Celsius. Dew point 12 degrees Celsius. Relative humidity 68 percent. Wind calm. Barometric pressure 1011 hectopascals, normal. Visibility 16 kilometers.

National Weather Service forecast. Values converted to SI units. Overnight: Partly cloudy, with a low around 17 degrees Celsius. West southwest wind 0.0 to 1.3 meters per second. Sunday: Partly sunny. High near 29 degrees Celsius, with temperatures falling to around 25 degrees Celsius in the afternoon. West northwest wind 0.4 to 5.4 meters per second. Sunday Night: Mostly clear, with a low around 16 degrees Celsius. West wind 0.0 to 4.0 meters per second.

Tide predictions for today at the San Francisco Embarcadero gauge. Low tide at 12:34 AM, minus 0.02 meters. High tide at 8:16 AM, 1.42 meters. Low tide at 12:48 PM, 1.00 meters. High tide at 6:32 PM, 1.72 meters.

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 1.0 meters, slight seas, dominant period 8 seconds, from the northwest. Wind at the buoy 2 meters per second from the west northwest. Ocean water temperature 15 degrees Celsius. San Francisco Bay water temperature 19 degrees Celsius. Golden Gate currents: slack water at 9:03 AM, then maximum ebb 0.8 meters per second at 11:39 AM, then slack water at 2:32 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 7 micrograms per cubic meter, rated good. Ozone is 19 parts per billion. Nitrogen dioxide is 16 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 2.4, near Alum Rock. No earthquakes of magnitude 6 or greater worldwide. Seismic data from earthquake.usgs.gov.

A significant local earthquake is the Bay Area's most likely trigger for ARES and RACES activation. Keep go-kits and backup power ready.