StarDust Ranch
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the StarDust Ranch clear sky chart from 2005-11-05 to 2018-04-23.

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
59%
16968
20%
49494
15%
16927
64%
16927
30%
31006

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 15thNight
44%
778
18%
2522
12%
776
54%
776
26%
1561
January16th to endNight
43%
832
26%
2678
17%
832
56%
832
30%
1566
February1st to 15thNight
46%
761
23%
2283
15%
758
56%
758
33%
1348
February16th to endNight
50%
683
31%
1922
18%
683
62%
683
40%
1072
March1st to 15thNight
47%
780
30%
2145
16%
780
60%
780
44%
1171
March16th to endNight
54%
832
28%
2288
19%
832
61%
832
45%
1252
April1st to 15thNight
59%
778
24%
2141
19%
778
64%
778
47%
1151
April16th to endNight
59%
743
27%
1871
16%
743
64%
743
43%
1114
May1st to 15thNight
67%
671
25%
1751
16%
671
71%
671
44%
1019
May16th to endNight
74%
561
21%
1682
16%
561
76%
561
34%
1018
June1st to 15thNight
66%
540
10%
1620
8%
540
66%
540
20%
1166
June16th to endNight
72%
540
10%
1620
9%
540
72%
540
22%
1151
July1st to 15thNight
70%
510
6%
1530
6%
510
70%
510
19%
1136
July16th to endNight
78%
564
8%
1595
8%
531
77%
531
22%
1133
August1st to 15thNight
77%
554
7%
1624
7%
551
77%
551
26%
1117
August16th to endNight
63%
764
6%
2035
5%
764
63%
764
19%
1509
September1st to 15thNight
66%
720
6%
1980
6%
720
66%
720
19%
1482
September16th to endNight
60%
717
9%
1980
9%
717
61%
717
18%
1466
October1st to 15thNight
66%
720
21%
2079
21%
720
69%
720
30%
1331
October16th to endNight
58%
768
24%
2304
22%
768
63%
768
29%
1429
November1st to 15thNight
62%
760
27%
2281
24%
760
70%
760
36%
1321
November16th to endNight
53%
780
30%
2340
24%
780
61%
780
33%
1401
December1st to 15thNight
54%
780
25%
2519
23%
780
61%
780
29%
1534
December16th to endNight
58%
832
23%
2704
22%
832
63%
832
32%
1558

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
7%5%37%7%47%6%7%8%33%
50006
Night
6%425%5%35%5%6%9%43%
49703
TransparencyDay
44%8%14%16%11%4
49707
Night
34%8%17%21%13%4
49506
SeeingDay
8%315%22%25%24%
6713
Night
8%317%32%28%9%
16976

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 15thDay
10%6%35%5%36%6%6%9%35%
1746
16th to endDay
9%425%5%35%5%7%7%43%
1895
February1st to 15thDay
9%5%246%35%47%7%42%
1900
16th to endDay
7%425%5%45%5%5%9%45%
1836
March1st to 15thDay
43246%35%5%7%8%48%
2145
16th to endDay
6%4245%36%5%6%8%46%
2287
April1st to 15thDay
5%325%5%47%6%7%9%41%
2137
16th to endDay
6%426%7%46%6%6%9%39%
2202
May1st to 15thDay
5%3247%47%5%6%9%43%
2208
16th to endDay
7%5%38%7%5%8%7%7%8%30%
2431
June1st to 15thDay
10%8%49%9%6%7%7%8%10%18%
2340
16th to endDay
7%6%48%10%6%9%8%7%8%21%
2340
July1st to 15thDay
10%6%49%10%5%8%7%9%8%17%
2340
16th to endDay
6%7%410%10%5%9%8%8%9%18%
2465
August1st to 15thDay
6%6%39%8%6%7%9%8%11%22%
2313
16th to endDay
9%7%5%9%10%5%9%7%7%7%19%
2163
September1st to 15thDay
7%6%410%10%7%9%6%8%9%19%
1980
16th to endDay
10%8%48%9%6%9%8%7%7%18%
1980
October1st to 15thDay
8%5%28%8%5%7%7%7%9%30%
1881
16th to endDay
8%7%35%6%45%6%6%8%37%
1920
November1st to 15thDay
5%426%6%5%5%7%6%8%40%
1907
16th to endDay
7%6%26%5%47%5%6%8%39%
1950
December1st to 15thDay
9%6%46%5%35%6%5%6%39%
1768
16th to endDay
5%325%437%5%7%10%43%
1872
January1st to 15thNight
8%6%35%5%345%6%9%40%
2522
16th to endNight
9%5%23425%45%8%46%
2678
February1st to 15thNight
10%415%43446%7%47%
2283
16th to endNight
5%31342445%8%54%
1922
March1st to 15thNight
3413425%349%57%
2145
16th to endNight
431341346%7%58%
2288
April1st to 15thNight
33134245%6%9%56%
2141
16th to endNight
6%213435%46%8%53%
1871
May1st to 15thNight
4323335%5%5%8%55%
1751
16th to endNight
5%324435%6%9%12%42%
1682
June1st to 15thNight
8%8%36%7%5%6%6%8%11%27%
1620
16th to endNight
6%5%26%7%5%6%7%8%11%32%
1620
July1st to 15thNight
9%5%36%7%35%6%7%11%31%
1620
16th to endNight
3436%7%48%8%8%11%32%
1703
August1st to 15thNight
3436%5%35%8%9%14%33%
1635
16th to endNight
11%6%36%6%35%6%8%13%28%
2035
September1st to 15thNight
7%5%36%7%48%7%8%13%27%
1980
16th to endNight
8%6%47%7%46%7%6%11%27%
1980
October1st to 15thNight
6%5%25%5%36%6%7%10%40%
2079
16th to endNight
9%6%2443445%9%44%
2304
November1st to 15thNight
43245%35%5%7%9%49%
2281
16th to endNight
7%425%5%35%45%8%47%
2340
December1st to 15thNight
8%425%5%36%5%5%7%45%
2519
16th to endNight
4425%436%5%7%8%46%
2704

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 15thDay
43%7%8%18%17%4
1747
16th to endDay
37%5%6%21%19%8%
1895
February1st to 15thDay
37%5%9%18%19%9%
1902
16th to endDay
34%5%11%19%20%9%
1836
March1st to 15thDay
32%6%10%23%19%8%
2145
16th to endDay
34%5%11%21%18%7%
2288
April1st to 15thDay
35%7%13%20%18%4
2137
16th to endDay
38%6%9%17%20%6%
2202
May1st to 15thDay
34%7%12%20%18%6%
2208
16th to endDay
48%7%13%18%10%1
2435
June1st to 15thDay
55%9%16%14%3
2340
16th to endDay
56%11%18%11%2
2340
July1st to 15thDay
56%14%20%7%1
2201
16th to endDay
54%14%20%10%
2310
August1st to 15thDay
50%12%28%8%
2300
16th to endDay
57%13%21%6%
2163
September1st to 15thDay
54%13%20%9%1
1980
16th to endDay
57%11%18%9%2
1980
October1st to 15thDay
46%8%12%14%13%3
1881
16th to endDay
43%6%7%14%19%8%
1920
November1st to 15thDay
38%6%8%21%16%8%
1907
16th to endDay
40%6%7%18%15%10%
1950
December1st to 15thDay
43%7%10%19%13%6%
1768
16th to endDay
34%6%13%24%15%6%
1872
January1st to 15thNight
38%6%14%20%14%5%
2522
16th to endNight
35%410%25%16%7%
2678
February1st to 15thNight
33%411%20%19%10%
2292
16th to endNight
26%5%12%24%23%7%
1922
March1st to 15thNight
24%413%29%21%7%
2145
16th to endNight
23%5%15%26%20%8%
2288
April1st to 15thNight
23%419%28%18%5%
2141
16th to endNight
26%6%14%24%22%5%
1871
May1st to 15thNight
26%5%13%30%16%7%
1752
16th to endNight
31%8%18%27%14%
1684
June1st to 15thNight
47%10%21%16%4
1620
16th to endNight
40%14%24%18%2
1620
July1st to 15thNight
43%15%25%13%1
1530
16th to endNight
36%18%28%15%1
1595
August1st to 15thNight
34%16%37%11%
1624
16th to endNight
43%15%28%11%
2035
September1st to 15thNight
44%16%24%13%2
1980
16th to endNight
47%13%20%14%4
1980
October1st to 15thNight
35%8%16%17%18%3
2079
16th to endNight
36%6%10%16%21%9%
2304
November1st to 15thNight
30%6%10%24%20%7%
2281
16th to endNight
34%5%10%23%17%9%
2340
December1st to 15thNight
36%5%11%24%14%7%
2519
16th to endNight
31%6%16%24%15%5%
2704

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 15thDay
15%13%40%20%6%3
135
16th to endDay
13%15%38%18%12%2
144
February1st to 15thDay
8%7%29%36%12%5%
135
16th to endDay
10%6%26%30%24%1
246
March1st to 15thDay
48%32%31%18%3
330
16th to endDay
5%7%24%31%23%6%
352
April1st to 15thDay
35%27%29%23%10%
330
16th to endDay
6%316%27%29%16%
289
May1st to 15thDay
5%211%28%34%17%
288
16th to endDay
8%29%17%35%26%
331
June1st to 15thDay
14%8%13%28%34%
315
16th to endDay
7%138%27%51%
315
July1st to 15thDay
7%16%26%58%
305
16th to endDay
10%210%21%54%
326
August1st to 15thDay
7%210%22%55%
313
16th to endDay
12%15%10%22%47%
332
September1st to 15thDay
8%5%12%24%48%
315
16th to endDay
10%217%27%40%
314
October1st to 15thDay
12%19%28%33%14%
315
16th to endDay
10%325%26%23%10%
336
November1st to 15thDay
9%114%31%31%11%
325
16th to endDay
6%323%39%23%3
330
December1st to 15thDay
9%6%38%25%17%2
148
16th to endDay
2317%40%29%5%
144
January1st to 15thNight
11%7%28%32%18%1
780
16th to endNight
11%8%31%35%13%
832
February1st to 15thNight
11%5%31%38%13%
764
16th to endNight
7%6%29%41%14%
683
March1st to 15thNight
5%6%36%37%12%1
780
16th to endNight
6%428%41%19%
832
April1st to 15thNight
4426%44%19%
778
16th to endNight
7%423%45%18%1
743
May1st to 15thNight
6%117%47%24%2
672
16th to endNight
5%18%34%40%9%
563
June1st to 15thNight
12%2323%44%13%
540
16th to endNight
8%215%45%27%
540
July1st to 15thNight
9%1111%44%31%
510
16th to endNight
41111%46%35%
564
August1st to 15thNight
5%111%46%34%
554
16th to endNight
12%15%15%41%24%
764
September1st to 15thNight
11%1313%47%23%
720
16th to endNight
13%1321%41%18%
717
October1st to 15thNight
10%18%35%34%8%
720
16th to endNight
13%216%31%30%4
768
November1st to 15thNight
6%219%40%27%3
760
16th to endNight
8%5%24%38%21%1
780
December1st to 15thNight
10%421%38%23%2
780
16th to endNight
5%5%22%37%25%3
832
Page generated at 2018-04-24 10:03:06. Version ac04

Copyright 2018 A. Danko


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