Report

Space weather: solar flux 105, 10 below its 90-day average of 115. Maximum usable frequency 16 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. Daytime absorption limits 160 and 80 meters to short range. 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, 37 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.

The maximum usable frequency usually peaks in early afternoon and falls after sunset, so higher band openings tend to be best from late morning to mid-afternoon.

Amateur satellite passes for the next four hours. SO 50, FM: at 12:07 PM rising in the southwest, 44 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: 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 6 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, 85 percent; a chance of ducting on 2 meters, 45 percent. Southern California coast, peaking around 1 PM: a chance of ducting on 70 centimeters, 50 percent; a slight chance of ducting on 2 meters, 10 percent. Nothing toward Hawaii.

Tropo openings favor horizontal antennas. Calling frequencies, upper sideband: 144.2 and 432.1 megahertz.

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.

Many handhelds can receive NOAA Weather Radio. Program the local channels.

Current weather conditions at San Francisco International Airport: Temperature 73 degrees Fahrenheit. Dew point 63 degrees Fahrenheit. Relative humidity 69 percent. Wind calm. Barometric pressure 29.90 inches of mercury, normal. Visibility 10 miles.

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. Today: Partly sunny. High near 85, with temperatures falling to around 77 in the afternoon. West northwest wind 1 to 12 miles per hour. Tonight: Mostly clear, with a low around 61. West wind 0 to 9 miles per hour. Monday: Sunny. High near 82, with temperatures falling to around 76 in the afternoon. West 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 15 seconds, from the south southwest. That's long-period ground swell. Wind at the buoy 4 knots from the northwest. Ocean water temperature 60 degrees Fahrenheit. San Francisco Bay water temperature 66 degrees Fahrenheit. Golden Gate currents: maximum ebb 1.5 knots at 11:39 AM, then slack water at 2:32 PM, then maximum flood 1.3 knots at 4:58 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 16 micrograms per cubic meter, rated moderate. Ozone is 13 parts per billion. Nitrogen dioxide is 22 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.