Report

Space weather: solar flux 105, 9 below its 90-day average of 114. Maximum usable frequency 19 megahertz, measured by the Idaho Falls ionosonde via KC2G: long-distance paths open through 20 meters, 17 meters marginal, 15 meters and up closed. Critical frequency 5.8 megahertz, so 80 meters is good for NVIS, 60 meters marginal. 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, 33 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.

VHF and UHF tropospheric enhancement is often strongest from sunset to early morning, when a nighttime temperature inversion forms.

Amateur satellite passes for the next four hours. FO 29, linear transponder, on a schedule: at 8:01 PM rising in the north northeast, 88 degrees, overhead. PO 101, FM, on a schedule: at 8:31 PM rising in the north northeast, 88 degrees, overhead. SO 50, FM: at 8:37 PM rising in the north northwest, 87 degrees, overhead. 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: 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 15 hours ago: Newer data is not yet available, and conditions may have changed. 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 4 AM: ducting expected on 70 centimeters, 85 percent; a chance of ducting on 2 meters, 45 percent. Southern California coast, peaking around 10 PM: ducting expected on 70 centimeters, 85 percent; a chance of ducting on 2 meters, 45 percent. Pacific Northwest coast, peaking around 1 AM: ducting expected on 70 centimeters, 80 percent; a slight chance of ducting on 2 meters, 25 percent. 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, 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.

Current weather conditions at San Francisco International Airport: Temperature 73 degrees Fahrenheit. Dew point 54 degrees Fahrenheit. Relative humidity 50 percent. Wind calm. Barometric pressure 29.88 inches of mercury, normal. Visibility 10 miles.

National Weather Service forecast. Tonight: Mostly clear, with a low around 61. West southwest wind 0 to 9 miles per hour. Monday: Sunny. High near 81, with temperatures falling to around 75 in the afternoon. West northwest wind 0 to 10 miles per hour. Monday Night: Mostly clear, with a low around 60. West southwest wind 2 to 9 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 10 knots from the west northwest. Ocean water temperature 61 degrees Fahrenheit. San Francisco Bay water temperature 67 degrees Fahrenheit. Golden Gate currents: maximum ebb 3.1 knots at 11:14 PM, then slack water at 4:09 AM, then maximum flood 2.1 knots at 6:50 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 5 micrograms per cubic meter, rated good. Ozone is 46 parts per billion. Nitrogen dioxide is 6 parts per billion. For more information visit the Bay Area Air District or openaq.org on the web.

Sign up for your county's emergency alerts, such as Alert SF in San Francisco. Hams are often among the first to relay that information.

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 2.5, near Pinnacles. 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.