Report

Space weather: solar flux 105, 10 below its 90-day average of 115. Maximum usable frequency 7 megahertz, measured by the Idaho Falls ionosonde via KC2G: long-distance paths limited to the low bands, 40 meters marginal, 30 meters and up closed. Critical frequency 2.7 megahertz, too low for NVIS right now. K index 4, minor geomagnetic storm. 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 7:08 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, 39 percent lit. The Orionid meteor shower peaks Wednesday, October 21, a meteor scatter opportunity on 6 and 2 meters. Moonbounce: the moon peaks today 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.

Grayline enhancement on 80 through 40 meters is strongest within about half an hour of sunrise and sunset.

Amateur satellite passes for the next four hours. RS 44, linear transponder, SSB and CW: at 6:24 AM rising in the north northwest, 41 degrees. FO 29, linear transponder, on a schedule: at 7:03 AM rising in the south southeast, 88 degrees, overhead. PO 101, FM, on a schedule: at 7:15 AM rising in the south southeast, 45 degrees. AO7, linear transponder: at 8:14 AM rising in the north northeast, 86 degrees, overhead. 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: passes above 30 degrees are the easiest. Low passes mean longer paths and more obstructions.

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 12 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 10 AM: a chance of ducting on 70 centimeters, 55 percent; a slight chance of ducting on 2 meters, 15 percent. Southern California coast, peaking around 4 PM: a chance of ducting on 70 centimeters, 40 percent; a slight chance of ducting on 2 meters, 10 percent. Nothing toward Hawaii.

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 64 degrees Fahrenheit. Dew point 55 degrees Fahrenheit. Relative humidity 73 percent. Wind calm. Barometric pressure 29.85 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. Overnight: Partly cloudy, with a low around 62. West southwest wind 0 to 3 miles per hour. Sunday: Partly sunny. High near 85, with temperatures falling to around 77 in the afternoon. West northwest wind 1 to 12 miles per hour. Sunday Night: Mostly clear, with a low around 61. West wind 0 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 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: maximum flood 1.9 knots at 5:40 AM, then slack water at 9:03 AM, then maximum ebb 1.5 knots at 11:39 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 10 micrograms per cubic meter, rated good. Ozone is 19 parts per billion. Nitrogen dioxide is 16 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.

Repeater sites can go off the air after a major earthquake. Program simplex frequencies and know your local simplex plan.