Somerton Creek
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Somerton Creek clear sky chart from 2005-11-06 to 2024-02-10.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
41%
23978
14%
79811
8%
23883
47%
23883
13%
58551

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 10thNight
25%
752
21%
4065
7%
737
35%
737
8%
2517
January11th to 20thNight
26%
758
21%
3971
6%
740
36%
740
7%
2616
January21st to endNight
24%
828
12%
4453
6%
814
38%
814
8%
3083
February1st to 10thNight
25%
759
14%
2464
6%
759
36%
759
13%
1824
February11th to 20thNight
16%
700
13%
2150
6%
700
25%
700
12%
1648
February21st to endNight
22%
592
18%
1776
6%
592
36%
592
13%
1335
March1st to 10thNight
28%
720
17%
2012
7%
720
38%
720
17%
1477
March11th to 20thNight
24%
720
13%
1980
5%
720
31%
720
12%
1573
March21st to endNight
27%
792
12%
2136
5%
792
32%
792
13%
1678
April1st to 10thNight
25%
720
14%
1800
3%
720
33%
720
17%
1389
April11th to 20thNight
32%
711
20%
1775
6%
711
39%
711
20%
1323
April21st to endNight
36%
720
16%
1800
6%
720
40%
720
19%
1379
May1st to 10thNight
35%
720
11%
1800
3%
720
39%
720
16%
1406
May11th to 20thNight
47%
516
12%
1578
7%
516
51%
516
12%
1265
May21st to endNight
60%
388
13%
1551
14%
388
62%
388
12%
1140
June1st to 10thNight
60%
360
14%
1440
16%
360
62%
360
13%
1023
June11th to 20thNight
56%
360
10%
1440
11%
360
59%
360
10%
1080
June21st to endNight
61%
360
12%
1440
13%
360
65%
360
12%
1078
July1st to 10thNight
62%
367
10%
1417
12%
367
62%
367
11%
1064
July11th to 20thNight
74%
522
9%
1566
7%
522
74%
522
17%
1183
July21st to endNight
62%
591
9%
1672
6%
558
64%
558
14%
1327
August1st to 10thNight
62%
537
8%
1600
6%
534
63%
534
15%
1221
August11th to 20thNight
60%
693
11%
1757
6%
693
61%
693
15%
1408
August21st to endNight
61%
792
9%
1980
5%
792
62%
792
15%
1601
September1st to 10thNight
62%
720
17%
1800
11%
720
63%
720
19%
1380
September11th to 20thNight
58%
720
18%
1800
13%
720
60%
720
18%
1401
September21st to endNight
45%
720
12%
2043
8%
720
49%
720
13%
1604
October1st to 10thNight
54%
720
16%
2160
14%
720
59%
720
17%
1604
October11th to 20thNight
45%
720
18%
2160
14%
720
52%
720
15%
1628
October21st to endNight
45%
792
18%
2376
13%
792
52%
792
16%
1758
November1st to 10thNight
44%
740
17%
2259
12%
740
51%
740
17%
1640
November11th to 20thNight
38%
760
16%
2470
11%
760
44%
760
14%
1832
November21st to endNight
43%
760
15%
2536
12%
760
49%
760
13%
1901
December1st to 10thNight
29%
760
14%
2660
6%
760
40%
760
11%
1990
December11th to 20thNight
33%
760
15%
3178
8%
759
42%
759
10%
2267
December21st to endNight
31%
828
11%
4746
7%
817
41%
817
8%
2908

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
14%6%25%5%35%5%5%8%43%
78370
Night
14%6%25%5%3445%7%44%
80592
TransparencyDay
27%36%7%15%12%3
78087
Night
27%35%7%14%13%3
80394
SeeingDay
17%11%26%25%16%5%
14219
Night
16%8%28%32%14%1
24008

By Month

Percentage Cloud Cover SE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
17%6%24323445%50%
2770
11th to 20thDay
14%7%2442345%6%49%
2840
21st to endDay
16%9%36%434345%42%
3124
February1st to 10thDay
13%7%25%5%35%447%44%
1701
11th to 20thDay
21%6%23434335%46%
1696
21st to endDay
19%6%26%5%3445%8%37%
1480
March1st to 10thDay
15%7%25%323436%51%
1944
11th to 20thDay
17%7%24433437%44%
1980
21st to endDay
17%7%25%5%35%447%41%
2218
April1st to 10thDay
14%423423447%53%
2160
11th to 20thDay
11%4245%345%5%7%50%
2134
21st to endDay
12%6%26%6%345%5%6%45%
2160
May1st to 10thDay
13%436%5%35%5%6%9%42%
2165
11th to 20thDay
16%6%35%5%45%45%7%38%
2322
21st to endDay
12%6%37%5%36%6%6%9%39%
2725
June1st to 10thDay
11%5%246%46%7%7%10%39%
2520
11th to 20thDay
10%5%16%5%36%6%7%11%40%
2520
21st to endDay
9%426%7%46%6%7%12%36%
2520
July1st to 10thDay
9%5%25%6%46%7%7%12%37%
2497
11th to 20thDay
7%5%26%6%5%6%6%8%11%37%
2340
21st to endDay
7%436%7%5%7%7%8%10%35%
2547
August1st to 10thDay
11%5%37%7%46%7%7%10%31%
2327
11th to 20thDay
12%7%36%5%36%6%7%11%32%
2126
21st to endDay
10%6%36%7%5%6%7%7%9%35%
2376
September1st to 10thDay
14%5%26%6%36%5%7%9%38%
2160
11th to 20thDay
14%6%35%6%45%46%7%40%
2160
21st to endDay
19%7%36%6%35%447%36%
1910
October1st to 10thDay
17%6%345%34447%44%
1800
11th to 20thDay
15%6%35%434445%50%
1800
21st to endDay
13%5%25%434446%51%
1980
November1st to 10thDay
15%5%24435%345%51%
1817
11th to 20thDay
15%5%34323345%52%
1710
21st to endDay
15%423333446%51%
1639
December1st to 10thDay
17%6%35%5%2446%6%42%
1520
11th to 20thDay
15%6%24323336%54%
1910
21st to endDay
17%6%26%5%2345%6%44%
2772
January1st to 10thNight
14%7%35%4245%5%5%46%
4172
11th to 20thNight
16%7%36%42445%6%43%
4120
21st to endNight
19%7%35%5%34445%43%
4532
February1st to 10thNight
17%7%2442445%7%43%
2464
11th to 20thNight
21%8%24424446%40%
2148
21st to endNight
16%6%34433446%46%
1776
March1st to 10thNight
14%5%24425%44451%
2012
11th to 20thNight
17%6%246%36%46%6%40%
1980
21st to endNight
16%6%26%5%3435%7%43%
2136
April1st to 10thNight
13%6%245%245%6%6%46%
1800
11th to 20thNight
13%5%25%43335%6%51%
1775
21st to endNight
14%426%435%35%7%48%
1800
May1st to 10thNight
12%6%35%5%345%6%8%41%
1800
11th to 20thNight
15%6%245%45%5%7%9%40%
1577
21st to endNight
12%5%25%445%5%6%9%43%
1550
June1st to 10thNight
11%4246%45%5%7%12%42%
1440
11th to 20thNight
9%5%36%6%45%5%7%11%40%
1440
21st to endNight
8%5%25%6%45%6%7%10%42%
1440
July1st to 10thNight
7%5%35%6%45%6%7%11%40%
1458
11th to 20thNight
6%435%5%46%7%8%10%42%
1620
21st to endNight
8%5%35%6%46%7%9%12%36%
1771
August1st to 10thNight
9%5%38%6%445%6%11%39%
1611
11th to 20thNight
9%7%37%6%35%6%8%10%36%
1757
21st to endNight
10%7%37%6%345%7%10%39%
1980
September1st to 10thNight
11%6%25%4345%7%9%44%
1800
11th to 20thNight
12%5%36%6%3445%7%45%
1800
21st to endNight
18%7%37%5%35%35%7%36%
2043
October1st to 10thNight
14%5%25%42345%6%49%
2160
11th to 20thNight
15%7%24434445%49%
2160
21st to endNight
13%5%245%23446%52%
2376
November1st to 10thNight
16%6%24323445%50%
2259
11th to 20thNight
16%6%3332345%6%49%
2470
21st to endNight
13%425%5%3445%7%49%
2536
December1st to 10thNight
17%7%36%5%34346%41%
2660
11th to 20thNight
18%6%24434446%46%
3285
21st to endNight
15%6%245%34447%45%
4884

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
27%24%5%23%18%2
2771
11th to 20thDay
27%25%6%13%24%5%
2840
21st to endDay
38%23%7%14%14%4
3124
February1st to 10thDay
27%34%7%17%12%3
1701
11th to 20thDay
27%37%413%16%4
1705
21st to endDay
30%36%7%11%13%3
1480
March1st to 10thDay
21%36%6%19%15%3
1944
11th to 20thDay
28%37%7%13%11%4
1980
21st to endDay
31%38%7%12%11%1
2218
April1st to 10thDay
20%36%8%16%15%5%
2160
11th to 20thDay
22%36%7%15%15%5%
2134
21st to endDay
26%38%7%14%12%3
2160
May1st to 10thDay
26%38%10%15%10%2
2165
11th to 20thDay
33%38%7%13%7%2
2326
21st to endDay
26%40%8%17%8%1
2725
June1st to 10thDay
25%39%9%15%11%1
2520
11th to 20thDay
26%40%10%15%9%1
2520
21st to endDay
27%40%9%14%8%2
2520
July1st to 10thDay
25%42%10%14%7%2
2428
11th to 20thDay
24%42%12%13%7%2
2271
21st to endDay
26%43%13%13%5%
2405
August1st to 10thDay
29%40%10%14%6%
2314
11th to 20thDay
29%39%9%14%8%1
2126
21st to endDay
31%40%10%10%8%2
2376
September1st to 10thDay
26%40%8%11%13%3
2160
11th to 20thDay
27%38%6%15%13%2
2160
21st to endDay
33%36%6%11%12%2
1910
October1st to 10thDay
27%36%413%17%3
1800
11th to 20thDay
27%36%415%15%3
1800
21st to endDay
25%37%412%18%3
1980
November1st to 10thDay
20%40%5%16%16%3
1817
11th to 20thDay
21%40%8%15%13%3
1710
21st to endDay
23%39%5%15%15%3
1639
December1st to 10thDay
23%41%7%14%13%2
1520
11th to 20thDay
24%32%5%20%13%6%
1906
21st to endDay
29%25%7%22%15%1
2772
January1st to 10thNight
29%25%7%19%17%3
4172
11th to 20thNight
32%25%5%16%18%3
4120
21st to endNight
37%24%5%14%14%5%
4532
February1st to 10thNight
28%34%5%16%13%4
2464
11th to 20thNight
29%37%5%13%13%4
2150
21st to endNight
27%37%6%13%13%5%
1776
March1st to 10thNight
23%36%7%16%15%3
2012
11th to 20thNight
30%37%7%12%11%3
1980
21st to endNight
29%37%8%13%11%2
2136
April1st to 10thNight
25%36%7%12%15%5%
1800
11th to 20thNight
22%36%6%15%16%5%
1775
21st to endNight
24%37%7%16%13%3
1800
May1st to 10thNight
25%39%10%16%9%1
1800
11th to 20thNight
30%40%7%11%10%2
1578
21st to endNight
23%41%10%17%8%1
1551
June1st to 10thNight
22%39%10%18%10%
1440
11th to 20thNight
27%40%11%13%9%1
1440
21st to endNight
25%41%10%13%8%2
1440
July1st to 10thNight
23%43%11%12%9%2
1417
11th to 20thNight
19%43%14%14%7%2
1566
21st to endNight
24%44%12%16%4
1672
August1st to 10thNight
24%40%16%14%5%
1600
11th to 20thNight
27%41%10%14%8%
1757
21st to endNight
28%40%10%14%7%1
1980
September1st to 10thNight
22%40%9%14%12%4
1800
11th to 20thNight
25%38%7%14%15%2
1800
21st to endNight
30%37%6%10%14%2
2043
October1st to 10thNight
24%37%413%18%3
2160
11th to 20thNight
28%36%5%14%14%3
2160
21st to endNight
24%37%5%13%16%5%
2376
November1st to 10thNight
19%40%6%14%18%3
2259
11th to 20thNight
23%40%7%12%15%4
2470
21st to endNight
24%40%5%14%14%3
2536
December1st to 10thNight
25%40%7%13%14%2
2660
11th to 20thNight
29%33%6%13%16%4
3288
21st to endNight
28%26%9%19%17%1
4884

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
21%26%34%13%5%
252
11th to 20thDay
23%28%33%15%1
270
21st to endDay
23%23%39%12%21
297
February1st to 10thDay
16%25%40%14%4
267
11th to 20thDay
29%23%30%15%4
364
21st to endDay
25%21%33%16%5%
346
March1st to 10thDay
20%21%36%17%6%
420
11th to 20thDay
23%19%35%18%5%1
420
21st to endDay
22%19%35%18%5%2
462
April1st to 10thDay
21%16%36%18%7%1
420
11th to 20thDay
14%18%33%21%12%2
412
21st to endDay
17%15%31%27%9%2
420
May1st to 10thDay
17%15%35%23%9%2
423
11th to 20thDay
20%6%28%28%15%3
447
21st to endDay
20%420%30%20%6%
485
June1st to 10thDay
14%5%22%32%22%5%
450
11th to 20thDay
12%7%19%33%23%7%
450
21st to endDay
10%420%36%24%6%
450
July1st to 10thDay
11%212%36%30%10%
445
11th to 20thDay
7%212%36%33%11%
444
21st to endDay
9%117%39%26%9%
488
August1st to 10thDay
13%217%32%26%10%
446
11th to 20thDay
13%312%27%32%13%
439
21st to endDay
10%314%31%28%15%
495
September1st to 10thDay
14%317%27%22%16%
450
11th to 20thDay
14%417%28%24%13%
450
21st to endDay
25%9%19%24%16%7%
450
October1st to 10thDay
20%6%19%25%21%9%
450
11th to 20thDay
15%10%27%26%19%3
450
21st to endDay
15%11%30%26%15%4
495
November1st to 10thDay
17%8%31%27%13%4
435
11th to 20thDay
18%15%32%23%11%2
370
21st to endDay
19%16%25%24%14%2
299
December1st to 10thDay
23%15%40%14%7%1
180
11th to 20thDay
19%17%35%21%8%1
180
21st to endDay
24%18%27%21%10%2
198
January1st to 10thNight
18%15%36%26%4
760
11th to 20thNight
21%13%34%25%6%
760
21st to endNight
19%12%40%27%2
836
February1st to 10thNight
20%12%39%25%4
759
11th to 20thNight
26%16%39%17%2
703
21st to endNight
21%16%38%23%3
592
March1st to 10thNight
18%13%38%27%5%
720
11th to 20thNight
20%13%39%21%6%
720
21st to endNight
20%12%37%26%5%
792
April1st to 10thNight
18%13%42%23%4
720
11th to 20thNight
14%12%39%26%9%
711
21st to endNight
17%8%36%33%6%
720
May1st to 10thNight
16%12%34%31%7%
720
11th to 20thNight
16%6%26%40%11%1
516
21st to endNight
12%217%49%19%1
389
June1st to 10thNight
11%320%47%18%1
360
11th to 20thNight
7%321%46%22%1
360
21st to endNight
9%218%49%20%1
360
July1st to 10thNight
11%114%47%25%2
367
11th to 20thNight
7%110%43%36%3
522
21st to endNight
8%217%45%27%2
591
August1st to 10thNight
9%212%44%29%4
537
11th to 20thNight
13%212%43%27%3
693
21st to endNight
12%212%33%36%4
792
September1st to 10thNight
14%212%37%29%6%
720
11th to 20thNight
14%314%35%29%4
720
21st to endNight
22%6%18%33%20%1
720
October1st to 10thNight
17%318%33%26%3
720
11th to 20thNight
19%5%26%31%17%1
720
21st to endNight
16%7%27%32%16%2
792
November1st to 10thNight
18%7%26%32%14%3
740
11th to 20thNight
18%9%30%33%9%1
760
21st to endNight
15%9%29%34%11%1
760
December1st to 10thNight
21%11%32%29%7%
760
11th to 20thNight
17%9%35%31%8%
760
21st to endNight
17%14%32%30%6%
836
Page generated at 2024-02-07 06:11:55. Version ac07

Copyright 2024 Attilla Danko


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