Solar Hills Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Solar Hills Observatory clear sky chart from 2005-11-05 to 2018-02-13.

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
60%
16485
25%
48822
21%
16446
64%
16446
37%
27943

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
59%
829
22%
2573
21%
827
61%
827
32%
1516
January16th to endNight
57%
832
25%
2704
27%
832
59%
832
30%
1587
February1st to 15thNight
50%
746
17%
2444
18%
746
53%
746
26%
1530
February16th to endNight
45%
632
24%
1935
18%
632
54%
632
30%
1179
March1st to 15thNight
55%
720
25%
1980
18%
720
60%
720
39%
1150
March16th to endNight
50%
765
22%
2109
17%
765
55%
765
32%
1331
April1st to 15thNight
44%
539
20%
1798
16%
539
50%
539
28%
1069
April16th to endNight
45%
540
23%
1800
18%
540
53%
540
28%
1048
May1st to 15thNight
53%
540
21%
1637
18%
539
57%
539
33%
948
May16th to endNight
57%
561
23%
1531
15%
561
62%
561
40%
867
June1st to 15thNight
65%
540
29%
1440
20%
540
71%
540
59%
713
June16th to endNight
78%
540
32%
1440
26%
540
81%
540
59%
709
July1st to 15thNight
80%
510
21%
1411
18%
510
81%
510
40%
805
July16th to endNight
82%
564
16%
1593
16%
531
83%
531
36%
925
August1st to 15thNight
80%
539
20%
1611
19%
536
81%
536
40%
885
August16th to endNight
79%
573
29%
1887
31%
573
80%
573
40%
995
September1st to 15thNight
78%
540
29%
1800
29%
540
81%
540
40%
935
September16th to endNight
71%
665
37%
1980
29%
665
78%
665
52%
969
October1st to 15thNight
64%
720
31%
2160
23%
720
69%
720
47%
1106
October16th to endNight
68%
768
35%
2304
28%
768
72%
768
48%
1178
November1st to 15thNight
59%
832
30%
2352
22%
832
63%
832
42%
1293
November16th to endNight
58%
975
29%
2691
22%
975
62%
975
44%
1483
December1st to 15thNight
50%
975
16%
2730
12%
975
53%
975
32%
1699
December16th to endNight
44%
1040
19%
2912
15%
1040
47%
1040
23%
2023

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
46%2442445%6%52%
49211
Night
46%24323446%55%
49012
TransparencyDay
31%7%12%20%19%8%
48900
Night
29%5%13%22%20%7%
48824
SeeingDay
9%10%28%30%17%2
6137
Night
8%5%20%37%25%2
16496

By Month

Percentage Cloud Cover SW (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
49%3442435%7%50%
1705
16th to endDay
411%35%322246%53%
1872
February1st to 15thDay
6%10%46%433447%43%
1683
16th to endDay
311%5%8%6%25%335%42%
1539
March1st to 15thDay
48%45%324345%52%
1977
16th to endDay
39%45%425%45%6%48%
2115
April1st to 15thDay
5%8%45%5%2345%7%47%
2150
16th to endDay
48%25%435%5%5%7%47%
2160
May1st to 15thDay
6%5%24435%5%6%7%47%
2311
16th to endDay
342443446%8%53%
2579
June1st to 15thDay
321432345%6%62%
2520
16th to endDay
1112223446%69%
2520
July1st to 15thDay
22136%36%7%6%9%48%
2461
16th to endDay
4415%5%47%8%8%10%39%
2467
August1st to 15thDay
5%426%5%46%7%7%8%40%
2340
16th to endDay
33145%36%5%8%8%48%
2313
September1st to 15thDay
5%3144345%6%6%52%
2160
16th to endDay
4213324436%63%
1975
October1st to 15thDay
6%41322345%6%59%
1800
16th to endDay
5%413312235%64%
1920
November1st to 15thDay
35%13423345%62%
1824
16th to endDay
342431323464%
1596
December1st to 15thDay
6%11%37%41324449%
1560
16th to endDay
5%15%5%8%424445%39%
1664
January1st to 15thNight
49%35%422335%54%
2573
16th to endNight
6%11%35%32223453%
2704
February1st to 15thNight
6%10%47%5%23235%48%
2433
16th to endNight
411%45%5%33345%48%
1935
March1st to 15thNight
36%35%324447%54%
1980
16th to endNight
5%8%35%424446%49%
2109
April1st to 15thNight
5%6%45%5%25%45%6%47%
1798
16th to endNight
7%7%35%42345%5%49%
1800
May1st to 15thNight
7%5%2442346%7%50%
1637
16th to endNight
6%41332445%7%57%
1531
June1st to 15thNight
121221335%7%69%
1440
16th to endNight
2112235%45%70%
1440
July1st to 15thNight
31125%245%8%9%54%
1495
16th to endNight
1135%36%6%10%14%45%
1701
August1st to 15thNight
32133345%6%9%56%
1620
16th to endNight
321342446%10%55%
1887
September1st to 15thNight
32133345%6%9%55%
1800
16th to endNight
421222224469%
1980
October1st to 15thNight
4313223346%64%
2160
16th to endNight
5%5%13212235%65%
2304
November1st to 15thNight
45%23312335%62%
2352
16th to endNight
5%6%14312345%61%
2691
December1st to 15thNight
6%11%36%313336%50%
2730
16th to endNight
6%14%5%8%5%23335%41%
2912

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
33%8%20%25%12%1
1706
16th to endDay
33%5%16%29%11%2
1872
February1st to 15thDay
41%7%16%21%10%2
1683
16th to endDay
43%5%8%24%16%1
1539
March1st to 15thDay
32%5%13%27%18%2
1977
16th to endDay
35%6%11%26%16%3
2115
April1st to 15thDay
36%5%12%21%17%6%
2150
16th to endDay
34%6%13%23%18%3
2160
May1st to 15thDay
36%8%10%21%20%2
2311
16th to endDay
28%8%12%19%25%6%
2582
June1st to 15thDay
21%37%16%27%23%
2520
16th to endDay
16%46%12%30%30%
2520
July1st to 15thDay
30%10%12%12%15%19%
2316
16th to endDay
35%14%14%17%10%7%
2312
August1st to 15thDay
37%11%12%14%13%10%
2325
16th to endDay
30%9%14%16%20%9%
2313
September1st to 15thDay
30%8%10%12%25%12%
2160
16th to endDay
23%7%8%18%32%9%
1975
October1st to 15thDay
25%6%9%25%27%6%
1800
16th to endDay
23%5%9%28%27%4
1920
November1st to 15thDay
23%6%11%23%28%6%
1824
16th to endDay
24%411%35%20%3
1596
December1st to 15thDay
38%5%15%23%14%1
1560
16th to endDay
48%7%15%19%8%
1664
January1st to 15thNight
31%7%16%26%15%1
2573
16th to endNight
36%413%28%14%2
2704
February1st to 15thNight
39%6%16%23%11%2
2444
16th to endNight
37%413%23%19%1
1935
March1st to 15thNight
28%5%15%29%19%2
1980
16th to endNight
35%5%10%24%21%3
2109
April1st to 15thNight
35%6%11%20%19%6%
1798
16th to endNight
34%6%11%21%20%5%
1800
May1st to 15thNight
30%7%13%21%20%5%
1638
16th to endNight
25%6%15%19%25%7%
1532
June1st to 15thNight
14%49%17%28%25%
1440
16th to endNight
14%45%12%26%36%
1440
July1st to 15thNight
24%9%13%16%14%21%
1411
16th to endNight
24%12%22%18%11%10%
1593
August1st to 15thNight
23%9%18%20%14%14%
1611
16th to endNight
23%7%14%19%21%12%
1887
September1st to 15thNight
23%7%14%17%21%16%
1800
16th to endNight
17%5%8%20%37%10%
1980
October1st to 15thNight
21%411%23%29%10%
2160
16th to endNight
23%39%27%31%5%
2304
November1st to 15thNight
25%5%11%25%26%6%
2352
16th to endNight
25%311%29%24%4
2691
December1st to 15thNight
35%6%17%22%16%1
2730
16th to endNight
47%5%14%21%10%
2912

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
17%7%17%32%21%3
135
16th to endDay
13%326%36%18%2
144
February1st to 15thDay
19%7%24%32%15%
126
16th to endDay
11%14%25%28%17%2
81
March1st to 15thDay
12%21%28%26%9%1
267
16th to endDay
17%23%34%18%5%
288
April1st to 15thDay
15%25%28%18%8%2
269
16th to endDay
19%24%35%15%4
270
May1st to 15thDay
13%20%34%22%8%1
288
16th to endDay
7%15%27%30%16%4
480
June1st to 15thDay
8%9%30%27%22%2
495
16th to endDay
3426%35%28%2
495
July1st to 15thDay
4220%37%29%5%
420
16th to endDay
7%221%40%22%4
327
August1st to 15thDay
8%326%39%16%5%
315
16th to endDay
6%225%41%21%3
332
September1st to 15thDay
7%5%33%35%13%4
315
16th to endDay
7%11%33%31%14%2
262
October1st to 15thDay
7%13%25%28%21%4
135
16th to endDay
8%9%20%35%20%4
144
November1st to 15thDay
7%8%30%25%25%1
135
16th to endDay
10%14%30%30%13%1
135
December1st to 15thDay
16%5%33%33%10%
135
16th to endDay
15%6%31%29%15%1
144
January1st to 15thNight
9%6%17%40%23%1
832
16th to endNight
12%420%39%19%4
832
February1st to 15thNight
13%5%24%40%16%
752
16th to endNight
10%8%30%38%11%
632
March1st to 15thNight
7%6%26%38%19%1
720
16th to endNight
9%7%27%35%19%
765
April1st to 15thNight
7%10%32%34%12%1
539
16th to endNight
13%10%26%30%17%1
540
May1st to 15thNight
9%6%25%40%16%1
540
16th to endNight
8%6%22%35%22%3
563
June1st to 15thNight
3424%36%28%2
540
16th to endNight
2212%44%35%3
540
July1st to 15thNight
46%40%45%2
510
16th to endNight
26%33%52%5%
564
August1st to 15thNight
5%17%35%45%4
539
16th to endNight
48%35%44%6%
573
September1st to 15thNight
3111%40%38%4
540
16th to endNight
6%216%30%36%7%
665
October1st to 15thNight
6%322%38%25%3
720
16th to endNight
8%216%37%29%5%
768
November1st to 15thNight
8%5%22%35%24%2
832
16th to endNight
10%7%21%36%21%3
975
December1st to 15thNight
13%6%24%37%16%1
975
16th to endNight
13%10%22%38%14%1
1040
Page generated at 2018-02-13 18:45:59. Version ac04

Copyright 2018 A. Danko


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