Report

Space weather: solar flux 105, 10 below its 90-day average of 115. Maximum usable frequency 27 megahertz, measured by the Idaho Falls ionosonde via KC2G: long-distance paths open through 15 meters, 12 meters marginal, 10 meters and up closed. Critical frequency 7.8 megahertz, so 80 and 60 meters are good for NVIS, 40 meters marginal. Daytime absorption limits 160 and 80 meters to short range. K index 2, 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, 48 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.

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. The ISS, FM crossband repeater, when active: at 11:17 AM rising in the west southwest, 54 degrees. SO 50, FM: at 11:49 AM rising in the south southwest, 89 degrees, overhead. For the next pass, the ISS: uplink 145.99 megahertz with a 67 hertz tone, downlink 437.8. Frequencies and live status at amsat.org/status. Pass predictions at n2yo.com.

Satellite tip: on 70 centimeter downlinks, Doppler shift is about plus or minus 10 kilohertz. Start high at rise and tune down through the pass.

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 700 to 1900 feet, good for 2 meters and up. A matching duct over Vandenberg suggests a path to Southern California. K6EEG's experimental tropo model, from NOAA data, for the next 12 hours: Ducting continues along the Bay Area coast, strongest around 5 PM, and the Southern California coast. Ducting developing along the Pacific Northwest coast after 8 PM. Nothing toward Hawaii.

Tropo openings favor horizontal antennas. For CW, try 144.05 to 144.1 megahertz on 2 meters, and 432.1 on 70 centimeters.

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: Temperature 68 degrees Fahrenheit. Dew point 61 degrees Fahrenheit. Relative humidity 78 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.

National Weather Service forecast. Today: Sunny. High near 86, with temperatures falling to around 80 in the afternoon. North wind 2 to 10 miles per hour. Tonight: Mostly clear, with a low around 63. West southwest wind 1 to 9 miles per hour. Sunday: Mostly cloudy. High near 84, with temperatures falling to around 76 in the afternoon. Northwest wind 1 to 10 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 4 feet, slight seas, dominant period 8 seconds, from the northwest. Wind at the buoy 6 knots from the north northwest. Ocean water temperature 60 degrees Fahrenheit. San Francisco Bay water temperature 66 degrees Fahrenheit. Golden Gate currents: slack water at 1 PM, then maximum flood 1.4 knots at 3:44 PM, then slack water at 5:36 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 9 micrograms per cubic meter, rated good. Ozone is 16 parts per billion. Nitrogen dioxide is 12 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.