RADIOMETEO · IZ6CLV

Ham Radio Weather

Propagation now

Ham radio weather in real time: propagation and space weather calculated for grid locator JN62WO.

Best bands now:30m 81%40m 77%80m 70%
Solar flux115SFI
Sunspots66SN
K index3.7NOAA estimated Kp
A index9A
X-rayB5.5R0
Geomagnetic fieldUnsettledNOAA SWPC

HF — shortwave

Band-by-band estimate and the useful frequencies for ionospheric contacts.

Bands now

160m64%Fair
80m70%Good
40m77%Good
30m81%Good
20m43%Poor
17m24%Closed
15m12%Closed
12m0%Closed
10m0%Closed
6m2%Closed

Next 24 hours, band by band

Grid times:
UTC040608101214161820220002
6mClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosed
10mClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosed
12mClosedClosedClosedClosedClosedClosedPoorPoorPoorPoorPoorPoorClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosedClosed
15mClosedClosedClosedClosedPoorPoorFairFairFairFairFairPoorPoorPoorClosedClosedClosedClosedClosedClosedClosedClosedClosedClosed
17mClosedClosedPoorClosedPoorPoorGoodGoodGoodGoodFairFairPoorPoorPoorPoorPoorPoorPoorPoorPoorPoorPoorPoor
20mPoorPoorPoorPoorGoodGoodGoodGoodGoodGoodGoodExcellentGoodFairFairFairFairFairFairFairFairFairFairFair
30mGoodGoodGoodGoodFairFairFairFairFairFairFairGoodGoodGoodGoodGoodGoodGoodGoodGoodGoodGoodGoodGood
40mGoodGoodGoodGoodFairPoorFairFairFairFairFairFairGoodGoodGoodGoodGoodGoodGoodGoodGoodGoodGoodGood
80mGoodGoodFairFairPoorPoorPoorPoorPoorPoorPoorPoorGoodGoodGoodGoodGoodGoodGoodGoodGoodGoodGoodGood
160mFairFairFairPoorClosedClosedClosedClosedClosedClosedClosedClosedPoorFairFairFairFairFairFairFairFairFairFairFair
ExcellentGoodFairPoorClosed

Critical frequencies

RadioMeteo model values (Boulder MUF from HamQSL when available).

foF24.5 MHzF2-layer critical frequency (vertical incidence)
MUF(3000)12.9 MHzmaximum usable frequency on a 3000 km hop
FOT11.0 MHzoptimum working frequency (85% of MUF)
LUF1.6 MHzlowest usable frequency: below it absorption dominates

MUF by distance

Maximum usable frequency for a hop of the given length.

500 km7.4 MHz
1,500 km10.2 MHz
3,000 km11.9 MHz
4,000 km13.4 MHz

MUF over the next 24 hours

Forecast maximum usable frequency hour by hour (UTC) for a 3000 km hop.

maximum 17.9 MHzminimum 12.9 MHz0–20 MHz · UTC

VHF and UHF

Phenomena that open the bands from 6 m upwards: Sporadic-E, tropospheric propagation and aurora.

Sporadic-E (Es)

3%climatological probability

estimated foEs3.3 MHz

  • MUF Es 500 km7.7 MHz
  • MUF Es 1000 km11.0 MHz
  • MUF Es 1500 km12.9 MHz
  • MUF Es 2000 km14.2 MHz

Tropospheric propagation (ducting)

Absentscore 10

Refractivity gradient-65 N/km

Surface refractivity331 N

Aurora

VHF aurora (northern hemisphere, HamQSL)Closed

Kp3.7

With Kp 5 or more, auroral openings towards the north can appear on VHF.

Es conditions reported by HamQSL
  • Europe 2 mClosed
  • Europe 4 mClosed
  • Europe 6 mClosed
  • North America 2 mClosed

Sun and magnetic field

Solar activity, official alerts and the Kp index forecast.

Flares and X-rays

B5.5

NOAA R scale (radio blackout)R0

No radio blackout in progress.

Latest NOAA alert

ALERT: Geomagnetic K-index of 5

Kp index: next 3 days

Thu 22Fri 23Sat 24Sun 25
QuietUnsettledActiveStorm

3-hour blocks (UTC).

Grey line at your QTH (JN62WO)

Sunrise
Sunset
At the antipodes
Sunrise
Sunset

Around sunrise and sunset the low bands open towards distant paths along the grey line.

Maps: HF absorption and aurora

Official NOAA maps, updated by the site every 15 minutes.

HF absorption (D-RAP)

HF absorption (D-RAP)

Image updated at 03:02 UTC · 05:02 local time

Shows, for each area, the highest frequency (MHz) degraded by 1 dB of absorption after solar flares. The higher the colour scale, the more HF bands are affected. With no flares the map is dark: no absorption.

Source: NOAA/NWS Space Weather Prediction Center

Aurora forecast · northern hemisphere

Aurora forecast · northern hemisphere

Image updated at 03:02 UTC · 05:02 local time

Probability of aurora (OVATION model). Useful for VHF aurora scatter and for polar HF paths, which degrade when the oval widens.

Source: NOAA/NWS Space Weather Prediction Center

Ham radio weather guide

What the indices mean and how to use them before going on air.

What ham radio weather is

Ham radio weather is the «weather» that matters for radio: solar activity and the state of the Earth’s magnetic field. The Sun charges the ionosphere, a high layer of the atmosphere that reflects shortwave signals and carries them far away. This page collects the official indices (NOAA SWPC and HamQSL) and turns them into a simple estimate: which HF bands are open now and over the next 24 hours from your locator, when Sporadic-E is worth trying on VHF and whether a magnetic storm is closing paths. It is an estimate: always confirm by listening to beacons and checking the DX Cluster.

Solar flux (SFI)

Measures solar activity at 10.7 cm. High values (above 120–150) favour the upper bands (17–10 m); low values (below 80) limit them.

K and A indices

Measure the disturbance of the Earth’s magnetic field. Kp up to 2 is quiet; 5 and above is a storm (NOAA G1–G5): the upper bands and polar paths degrade first.

X-rays and flares

An M or X class flare ionises the D layer and can black out HF on the sunlit side of the Earth for minutes or hours (NOAA R1–R5).

MUF, FOT and LUF

The MUF is the highest frequency returned to earth on a path; the best working point is around the FOT, about 85% of the MUF. Below the LUF signals are absorbed.

Sporadic-E

Thin ionised clouds at 90–120 km which, mostly from May to August, open 10 m, 6 m and sometimes 4 m and 2 m over 500–2000 km.

Tropospheric ducting

With high pressure and temperature inversions VHF/UHF can travel hundreds of kilometres: a strongly negative refractivity gradient shows it.

Model limits

The estimates on this page are simplified models (ITU-R P.1239/P.1240 concepts) based on solar and geomagnetic indices: they are not measurements. Always confirm by listening, beacons, the DX Cluster and the reverse beacon network.

Band conditions →DX Cluster →Beacons and WebSDR →

Sources: NOAA SWPC, N0NBH/HamQSL, Open-Meteo (ECMWF). RadioMeteo models. Updated