Report

Space weather: solar flux 105, 10 below its 90-day average of 115. Maximum usable frequency 21 megahertz, measured by the Idaho Falls ionosonde via KC2G: long-distance paths open through 17 meters, 15 meters marginal, 12 meters and up closed. Critical frequency 6.4 megahertz, so 80 and 60 meters are good for NVIS. 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.

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. RS 44, linear transponder, SSB and CW: at 6:35 PM rising in the south, 74 degrees, overhead. FO 29, linear transponder, on a schedule: at 7:12 PM rising in the north northeast, 31 degrees. 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, RS 44: inverting linear transponder, uplink near 435.64 megahertz lower sideband, downlink near 145.965 upper sideband. Frequencies and live status at amsat.org/status. Pass predictions at n2yo.com.

Satellite tip: image satellites are receive-only. An FM receiver and a phone app such as Robot 36 can decode their pictures; set the app to the satellite's mode, or let it detect the mode automatically.

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 2 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 3 AM: ducting expected on 70 centimeters, 90 percent; a chance of ducting on 2 meters, 55 percent. Southern California coast, peaking around 12 AM: a chance of ducting on 70 centimeters, 55 percent; a slight chance of ducting on 2 meters, 15 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.

Current weather conditions at San Francisco International Airport: All values in SI units. Clear. Temperature 29 degrees Celsius. Dew point 12 degrees Celsius. Relative humidity 35 percent. Wind calm. Barometric pressure 1009 hectopascals, low pressure. Visibility 16 kilometers.

Batteries and radios in parked cars degrade in heat. Keep go-kit batteries somewhere cool. Know how long your backup power lasts. Test it under real load, not just with a meter.

National Weather Service forecast. Values converted to SI units. This Afternoon: Sunny. High near 30 degrees Celsius, with temperatures falling to around 26 degrees Celsius in the afternoon. West northwest wind 2.2 to 5.4 meters per second. Tonight: Mostly clear, with a low around 17 degrees Celsius. West wind 0.0 to 4.0 meters per second. Sunday: Partly sunny. High near 28 degrees Celsius, with temperatures falling to around 24 degrees Celsius in the afternoon. Northwest wind 0.4 to 4.5 meters per second.

Tide predictions for today at the San Francisco Embarcadero gauge. High tide at 7:11 AM, 1.35 meters. Low tide at 11:12 AM, 1.08 meters. High tide at 5:11 PM, 1.77 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 1.1 meters, slight seas, dominant period 7 seconds, from the west northwest. Mostly short-period wind waves. Wind at the buoy 5 meters per second from the north northwest. Ocean water temperature 16 degrees Celsius. San Francisco Bay water temperature 20 degrees Celsius. Golden Gate currents: maximum ebb 1.7 meters per second at 9:40 PM, then slack water at 3:01 AM, then maximum flood 1.0 meters per second at 5:40 AM.

If you feel a strong or long-lasting earthquake near the coast, move to high ground immediately. Don't wait for an official tsunami warning.

Air quality for field operations, from the Bay Area Air District's San Francisco Arkansas Street monitoring station. Fine particulate matter, PM2.5, is 9 micrograms per cubic meter, rated good. Ozone is 46 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.

Text, don't call. Text messages often get through when voice calls can't, and they keep lines open for emergency calls.