Report

Space weather: solar flux 105, 10 below its 90-day average of 115. Maximum usable frequency 17 megahertz, measured by the Idaho Falls ionosonde via KC2G: long-distance paths open through 20 meters, 17 meters and up closed. Critical frequency 5.4 megahertz, so 80 meters is good for NVIS, 60 meters marginal. K index 3, unsettled. 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, 43 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.

160 and 80 meters often peak right at sunrise on paths to the west, just before the D layer forms and absorbs them.

Amateur satellite passes for the next four hours. AO 91, FM: at 9:35 PM rising in the north northeast, 41 degrees. For the next pass, AO 91: uplink 435.25 megahertz with a 67 hertz tone, downlink 145.96. 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 5 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, 85 percent; a chance of ducting on 2 meters, 45 percent. Southern California coast, peaking around 12 AM: ducting expected on 70 centimeters, 85 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, 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.

Check into a local net this week. Regular net practice is what makes emergency nets work. Test your go-kit monthly, and rotate batteries and supplies.

Current weather conditions at San Francisco International Airport: All values in SI units. Clear. Temperature 26 degrees Celsius. Dew point 12 degrees Celsius. Relative humidity 42 percent. Wind calm. Barometric pressure 1009 hectopascals, normal. Visibility 16 kilometers.

National Weather Service forecast. Values converted to SI units. Tonight: Mostly clear, with a low around 17 degrees Celsius. West wind 0.0 to 2.2 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. Sunday Night: Mostly clear, with a low around 16 degrees Celsius. West southwest wind 0.9 to 4.0 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 10 seconds, from the west. Wind at the buoy 6 meters per second from the 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.

Air quality for field operations, from the Bay Area Air District's San Francisco Arkansas Street monitoring station. Fine particulate matter, PM2.5, is 6 micrograms per cubic meter, rated good. Ozone is 33 parts per billion. Nitrogen dioxide is 9 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.

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