Goodsell Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Goodsell Observatory clear sky chart from 2005-11-06 to 2024-01-12.

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
35%
24821
17%
74716
9%
24762
42%
24762
23%
50260

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%
950
12%
2648
5%
946
32%
946
20%
1928
January11th to 20thNight
23%
910
11%
2515
5%
910
28%
910
16%
1932
January21st to endNight
21%
990
11%
2574
3%
990
27%
990
15%
2027
February1st to 10thNight
24%
900
14%
2340
3%
900
31%
900
21%
1714
February11th to 20thNight
25%
879
17%
2274
6%
875
32%
875
24%
1585
February21st to endNight
25%
674
16%
1858
5%
674
35%
674
20%
1342
March1st to 10thNight
30%
602
14%
2042
10%
602
35%
602
19%
1363
March11th to 20thNight
30%
540
18%
1980
11%
540
41%
540
18%
1288
March21st to endNight
32%
594
15%
2156
13%
594
40%
594
17%
1469
April1st to 10thNight
26%
540
15%
1800
9%
540
38%
540
19%
1214
April11th to 20thNight
31%
533
16%
1775
13%
533
40%
533
17%
1243
April21st to endNight
31%
540
17%
1626
9%
540
41%
540
21%
1122
May1st to 10thNight
31%
540
14%
1533
8%
540
37%
540
24%
1042
May11th to 20thNight
40%
531
19%
1417
9%
531
46%
531
30%
937
May21st to endNight
43%
584
14%
1552
6%
582
48%
582
27%
1048
June1st to 10thNight
49%
540
17%
1440
7%
540
53%
540
36%
888
June11th to 20thNight
47%
540
15%
1440
6%
540
50%
540
31%
928
June21st to endNight
58%
540
18%
1440
8%
540
60%
540
42%
845
July1st to 10thNight
66%
525
18%
1400
9%
525
68%
525
48%
767
July11th to 20thNight
62%
522
23%
1392
10%
522
66%
522
46%
787
July21st to endNight
68%
591
22%
1526
14%
558
71%
558
50%
823
August1st to 10thNight
65%
537
21%
1601
19%
534
68%
534
35%
944
August11th to 20thNight
61%
534
24%
1600
22%
534
67%
534
37%
919
August21st to endNight
57%
594
23%
1903
24%
594
64%
594
37%
1049
September1st to 10thNight
56%
540
24%
1800
24%
540
62%
540
34%
975
September11th to 20thNight
48%
540
27%
1818
20%
540
60%
540
33%
1021
September21st to endNight
40%
612
22%
2052
14%
612
50%
612
30%
1173
October1st to 10thNight
40%
720
22%
2160
14%
720
47%
720
30%
1315
October11th to 20thNight
29%
720
21%
2160
9%
720
39%
720
24%
1408
October21st to endNight
30%
792
18%
2390
10%
792
38%
792
20%
1616
November1st to 10thNight
29%
830
22%
2496
10%
830
41%
830
24%
1610
November11th to 20thNight
24%
950
16%
2660
6%
950
32%
950
19%
1930
November21st to endNight
24%
950
17%
2660
7%
950
33%
950
21%
1867
December1st to 10thNight
25%
950
11%
2660
4%
950
31%
950
18%
1950
December11th to 20thNight
20%
949
12%
3211
3%
948
28%
948
12%
2384
December21st to endNight
18%
1038
7%
4817
4%
1026
26%
1026
7%
3807

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
13%8%37%6%35%5%5%7%37%
74711
Night
13%9%47%6%3445%7%40%
75036
TransparencyDay
46%7%13%23%11%1
74414
Night
45%6%13%23%12%2
74853
SeeingDay
16%10%30%27%13%4
14809
Night
16%9%33%31%11%1
24829

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
8%11%8%9%8%5%8%5%46%28%
1517
11th to 20thDay
10%17%7%11%9%46%5%5%5%21%
1480
21st to endDay
9%13%6%12%10%47%6%6%7%20%
1782
February1st to 10thDay
9%9%5%10%9%46%7%6%7%27%
1620
11th to 20thDay
10%10%6%9%7%36%5%6%6%31%
1574
21st to endDay
14%10%49%7%36%5%46%31%
1397
March1st to 10thDay
14%11%5%9%6%345%47%31%
1934
11th to 20thDay
14%10%47%6%35%45%7%34%
1980
21st to endDay
20%11%37%6%34447%31%
2200
April1st to 10thDay
18%10%46%5%2446%8%33%
2160
11th to 20thDay
21%11%36%5%34445%33%
2134
21st to endDay
21%10%37%5%35%5%5%5%30%
2330
May1st to 10thDay
18%7%46%6%35%6%6%7%34%
2425
11th to 20thDay
17%7%35%5%3445%8%38%
2479
21st to endDay
16%6%26%6%45%5%5%7%38%
2725
June1st to 10thDay
12%5%25%5%345%6%9%46%
2520
11th to 20thDay
14%5%25%6%35%5%7%10%39%
2520
21st to endDay
10%5%25%6%36%6%6%10%41%
2520
July1st to 10thDay
7%425%5%335%7%10%50%
2520
11th to 20thDay
9%313435%5%6%8%52%
2520
21st to endDay
7%3245%35%6%7%9%48%
2699
August1st to 10thDay
9%436%6%46%6%7%8%42%
2328
11th to 20thDay
13%5%25%445%46%8%44%
2301
21st to endDay
9%4245%245%5%8%52%
2451
September1st to 10thDay
14%6%25%4345%5%8%45%
2160
11th to 20thDay
12%5%25%4345%6%6%49%
2139
21st to endDay
16%7%245%345%5%7%42%
1890
October1st to 10thDay
16%6%245%4446%6%43%
1800
11th to 20thDay
15%9%26%43445%7%41%
1800
21st to endDay
18%11%46%424447%35%
1965
November1st to 10thDay
11%10%46%6%3445%7%39%
1580
11th to 20thDay
11%12%7%10%7%36%446%30%
1520
21st to endDay
13%10%48%6%335%5%6%38%
1520
December1st to 10thDay
11%12%5%10%9%5%5%45%6%27%
1520
11th to 20thDay
10%12%7%9%7%36%5%5%6%29%
1918
21st to endDay
21%15%6%15%7%33345%18%
2783
January1st to 10thNight
9%9%6%10%8%45%6%46%32%
2648
11th to 20thNight
11%13%6%10%9%45%5%47%27%
2515
21st to endNight
12%14%5%12%7%45%5%5%5%25%
2574
February1st to 10thNight
6%12%6%9%7%45%5%47%33%
2340
11th to 20thNight
8%9%48%7%5%6%446%39%
2273
21st to endNight
13%9%49%6%45%35%6%36%
1858
March1st to 10thNight
13%10%47%5%3445%6%38%
2042
11th to 20thNight
13%10%37%7%4435%7%37%
1980
21st to endNight
17%9%47%5%2446%7%34%
2156
April1st to 10thNight
14%11%47%5%35%45%6%38%
1800
11th to 20thNight
21%10%45%5%34446%34%
1775
21st to endNight
19%9%36%6%35%447%36%
1626
May1st to 10thNight
18%8%26%5%3445%6%39%
1533
11th to 20thNight
15%5%25%43345%8%44%
1416
21st to endNight
14%6%35%5%35%5%5%7%42%
1551
June1st to 10thNight
9%5%25%4345%6%7%50%
1440
11th to 20thNight
10%6%25%5%45%5%6%8%45%
1440
21st to endNight
8%3235%2445%8%55%
1440
July1st to 10thNight
5%2134245%8%10%56%
1440
11th to 20thNight
432343446%10%57%
1440
21st to endNight
5%2233235%5%9%60%
1616
August1st to 10thNight
6%6%145%36%6%6%9%50%
1611
11th to 20thNight
10%425%32345%8%53%
1600
21st to endNight
8%42443345%6%57%
1903
September1st to 10thNight
10%425%424446%56%
1800
11th to 20thNight
13%424324446%54%
1818
21st to endNight
14%6%25%323346%52%
2052
October1st to 10thNight
16%5%24423446%50%
2160
11th to 20thNight
16%7%445%3445%7%42%
2160
21st to endNight
18%11%45%424346%38%
2390
November1st to 10thNight
12%9%45%4245%5%5%44%
2496
11th to 20thNight
12%11%6%10%7%34345%34%
2660
21st to endNight
14%9%48%6%34346%38%
2660
December1st to 10thNight
9%12%5%10%7%36%5%5%7%31%
2660
11th to 20thNight
12%12%5%9%8%45%5%5%7%28%
3279
21st to endNight
23%13%6%11%6%3444421%
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
56%6%13%19%6%
1518
11th to 20thDay
65%5%9%12%9%
1480
21st to endDay
62%6%13%12%7%1
1782
February1st to 10thDay
55%7%14%16%8%1
1620
11th to 20thDay
53%7%11%20%8%1
1583
21st to endDay
55%6%11%17%11%
1397
March1st to 10thDay
54%6%13%19%7%1
1934
11th to 20thDay
50%7%13%21%8%1
1980
21st to endDay
55%7%11%20%6%1
2200
April1st to 10thDay
50%6%12%20%11%1
2160
11th to 20thDay
53%5%11%19%11%2
2134
21st to endDay
56%6%12%18%7%1
2330
May1st to 10thDay
49%7%13%22%8%2
2425
11th to 20thDay
45%7%13%24%11%1
2483
21st to endDay
45%7%11%23%12%2
2725
June1st to 10thDay
34%9%13%29%13%1
2520
11th to 20thDay
41%7%13%23%15%1
2520
21st to endDay
38%9%17%24%10%2
2520
July1st to 10thDay
30%9%16%32%13%1
2451
11th to 20thDay
28%8%16%27%18%3
2445
21st to endDay
29%10%16%28%14%3
2549
August1st to 10thDay
36%8%14%29%9%3
2314
11th to 20thDay
37%7%14%29%12%
2301
21st to endDay
30%7%14%29%19%1
2451
September1st to 10thDay
36%6%13%29%15%
2160
11th to 20thDay
35%7%15%32%11%1
2139
21st to endDay
41%6%11%31%9%1
1890
October1st to 10thDay
42%5%10%29%13%1
1800
11th to 20thDay
43%414%23%13%1
1800
21st to endDay
50%5%12%23%9%1
1965
November1st to 10thDay
45%5%14%19%15%3
1580
11th to 20thDay
55%6%12%17%10%1
1520
21st to endDay
47%6%17%22%7%1
1520
December1st to 10thDay
58%6%16%12%7%
1520
11th to 20thDay
56%6%18%14%6%
1915
21st to endDay
70%5%9%11%4
2783
January1st to 10thNight
52%5%14%20%9%
2648
11th to 20thNight
58%6%14%16%6%1
2515
21st to endNight
60%5%12%15%8%1
2574
February1st to 10thNight
52%413%21%9%1
2340
11th to 20thNight
46%5%13%24%10%1
2274
21st to endNight
52%5%9%21%12%2
1858
March1st to 10thNight
48%5%16%23%8%1
2042
11th to 20thNight
47%5%12%22%13%1
1980
21st to endNight
50%6%12%23%8%2
2156
April1st to 10thNight
48%6%10%21%15%1
1800
11th to 20thNight
51%6%9%17%15%3
1775
21st to endNight
49%410%21%15%2
1626
May1st to 10thNight
45%5%14%21%14%1
1533
11th to 20thNight
38%7%14%24%14%3
1417
21st to endNight
41%7%12%21%17%2
1552
June1st to 10thNight
31%8%13%30%17%2
1440
11th to 20thNight
37%7%14%22%19%3
1440
21st to endNight
26%7%16%31%17%3
1440
July1st to 10thNight
21%7%15%35%19%3
1400
11th to 20thNight
22%7%14%34%19%4
1392
21st to endNight
21%6%18%33%18%4
1526
August1st to 10thNight
29%9%13%30%15%4
1601
11th to 20thNight
29%6%16%29%18%1
1600
21st to endNight
27%7%13%29%19%4
1903
September1st to 10thNight
29%6%11%34%20%1
1800
11th to 20thNight
31%6%14%31%17%1
1818
21st to endNight
35%413%31%16%1
2052
October1st to 10thNight
37%5%10%30%16%3
2160
11th to 20thNight
41%6%13%24%15%1
2160
21st to endNight
48%5%12%22%13%1
2390
November1st to 10thNight
41%6%13%24%15%2
2496
11th to 20thNight
52%5%11%19%12%1
2660
21st to endNight
48%5%15%23%8%1
2660
December1st to 10thNight
53%6%15%19%6%1
2660
11th to 20thNight
55%7%13%17%6%1
3281
21st to endNight
67%5%10%14%4
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
13%10%36%27%11%3
270
11th to 20thDay
17%13%34%29%6%2
245
21st to endDay
16%11%37%23%9%3
264
February1st to 10thDay
12%15%43%26%31
240
11th to 20thDay
16%14%40%23%7%
240
21st to endDay
20%13%37%28%3
198
March1st to 10thDay
18%13%42%20%6%1
240
11th to 20thDay
20%9%38%24%8%1
240
21st to endDay
29%13%24%22%9%2
286
April1st to 10thDay
25%13%36%20%6%1
420
11th to 20thDay
27%14%24%24%11%1
412
21st to endDay
26%12%29%20%11%3
590
May1st to 10thDay
19%13%32%25%8%2
603
11th to 20thDay
19%12%29%23%13%4
625
21st to endDay
19%9%25%29%15%3
679
June1st to 10thDay
10%8%26%31%20%5%
630
11th to 20thDay
15%6%33%33%10%3
630
21st to endDay
10%8%31%29%15%6%
630
July1st to 10thDay
7%5%23%30%24%10%
621
11th to 20thDay
10%5%28%31%19%8%
618
21st to endDay
7%424%39%20%6%
684
August1st to 10thDay
10%222%36%24%5%
626
11th to 20thDay
15%319%33%25%6%
615
21st to endDay
10%5%26%35%17%6%
570
September1st to 10thDay
15%8%28%29%14%5%
450
11th to 20thDay
12%6%31%31%17%4
429
21st to endDay
20%11%31%22%11%5%
270
October1st to 10thDay
19%7%31%26%13%5%
270
11th to 20thDay
17%19%36%21%6%1
270
21st to endDay
26%16%35%14%8%1
297
November1st to 10thDay
16%14%39%20%11%
270
11th to 20thDay
16%20%40%20%4
270
21st to endDay
22%13%41%19%4
270
December1st to 10thDay
16%10%39%26%8%1
270
11th to 20thDay
19%15%34%23%9%
270
21st to endDay
26%15%35%21%3
297
January1st to 10thNight
11%12%38%29%8%1
950
11th to 20thNight
17%11%37%28%6%1
910
21st to endNight
19%10%38%27%5%1
990
February1st to 10thNight
12%12%42%28%6%1
900
11th to 20thNight
13%12%43%25%7%1
879
21st to endNight
17%11%37%26%8%1
674
March1st to 10thNight
17%10%35%28%9%1
602
11th to 20thNight
17%10%37%29%6%1
540
21st to endNight
21%11%30%25%11%2
594
April1st to 10thNight
20%11%38%25%6%
540
11th to 20thNight
25%10%29%28%8%
533
21st to endNight
21%10%32%26%9%2
540
May1st to 10thNight
19%10%34%30%6%1
540
11th to 20thNight
17%7%31%34%10%1
531
21st to endNight
17%6%26%36%14%1
584
June1st to 10thNight
11%430%39%15%1
540
11th to 20thNight
12%431%42%11%
540
21st to endNight
9%324%48%16%1
540
July1st to 10thNight
6%121%42%27%2
525
11th to 20thNight
6%325%46%19%2
522
21st to endNight
5%221%51%20%2
591
August1st to 10thNight
6%220%45%24%2
537
11th to 20thNight
10%320%37%25%4
534
21st to endNight
9%226%38%23%2
594
September1st to 10thNight
11%5%25%38%17%4
540
11th to 20thNight
13%5%31%31%18%2
540
21st to endNight
14%9%33%29%14%
612
October1st to 10thNight
18%8%29%29%14%1
720
11th to 20thNight
19%12%36%26%7%1
720
21st to endNight
25%11%29%28%8%
792
November1st to 10thNight
17%13%36%27%7%1
830
11th to 20thNight
17%13%40%25%6%
950
21st to endNight
16%14%39%23%8%
950
December1st to 10thNight
15%10%40%28%6%1
950
11th to 20thNight
20%9%39%26%7%1
950
21st to endNight
24%11%35%26%4
1045
Page generated at 2024-01-09 15:24:27. Version ac07

Copyright 2024 Attilla Danko


Goodsell Observatory Clear Sky Chart |Charts Home