Orin
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Orin 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
42%
16733
24%
48798
14%
16690
52%
16690
36%
27661

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
35%
974
22%
2716
11%
970
45%
970
30%
1619
January16th to endNight
30%
953
27%
2825
12%
953
46%
953
33%
1575
February1st to 15thNight
32%
748
17%
2444
11%
747
41%
747
26%
1459
February16th to endNight
31%
632
22%
1897
8%
632
44%
632
28%
1136
March1st to 15thNight
35%
720
22%
2123
9%
720
48%
720
34%
1209
March16th to endNight
36%
678
21%
2022
11%
678
47%
678
29%
1242
April1st to 15thNight
33%
539
19%
1798
12%
539
45%
539
27%
1068
April16th to endNight
37%
540
17%
1793
12%
540
44%
540
24%
1108
May1st to 15thNight
45%
540
21%
1482
13%
540
51%
540
33%
912
May16th to endNight
48%
563
19%
1498
11%
561
53%
561
33%
940
June1st to 15thNight
47%
540
18%
1440
9%
540
53%
540
42%
822
June16th to endNight
54%
540
25%
1440
14%
540
59%
540
62%
706
July1st to 15thNight
61%
510
21%
1360
13%
510
66%
510
50%
733
July16th to endNight
64%
564
27%
1416
20%
531
68%
531
57%
714
August1st to 15thNight
65%
539
27%
1563
21%
536
71%
536
51%
780
August16th to endNight
67%
573
31%
1910
31%
573
74%
573
47%
914
September1st to 15thNight
57%
540
28%
1800
24%
540
67%
540
40%
919
September16th to endNight
57%
543
35%
1932
32%
543
68%
543
44%
903
October1st to 15thNight
46%
720
26%
2160
16%
720
53%
720
34%
1272
October16th to endNight
44%
837
33%
2373
15%
837
56%
837
42%
1315
November1st to 15thNight
41%
950
27%
2470
13%
950
49%
950
41%
1430
November16th to endNight
35%
975
30%
2694
11%
975
50%
975
39%
1500
December1st to 15thNight
30%
975
19%
2730
9%
975
40%
975
31%
1630
December16th to endNight
30%
1040
23%
2912
9%
1040
43%
1040
29%
1755

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
6%5%234245%5%8%51%
49257
Night
5%5%2442445%7%53%
48964
Cloud CoverDay
6%5%2442445%8%51%
49267
Night
5%5%2442445%7%52%
48969
TransparencyDay
29%413%26%18%7%
48940
Night
29%414%27%18%6%
48798
SeeingDay
10%9%29%29%17%3
6440
Night
8%10%33%34%11%
16738

By Month

Percentage Cloud Cover NE (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
1435%425%5%6%8%51%
1552
16th to endDay
36%2443335%7%54%
1762
February1st to 15thDay
49%344345%6%7%45%
1683
16th to endDay
310%45%42445%8%46%
1577
March1st to 15thDay
46%2433245%6%56%
1826
16th to endDay
7%6%245%25%45%8%47%
2202
April1st to 15thDay
9%6%3442445%9%45%
2150
16th to endDay
12%8%245%35%5%5%7%37%
2166
May1st to 15thDay
12%6%244345%6%7%41%
2468
16th to endDay
12%4245%36%6%6%9%38%
2616
June1st to 15thDay
7%413425%5%7%10%47%
2520
16th to endDay
221221345%9%65%
2520
July1st to 15thDay
4213325%6%6%9%55%
2520
16th to endDay
42133345%6%10%54%
2656
August1st to 15thDay
32134246%7%9%52%
2385
16th to endDay
42133235%47%59%
2292
September1st to 15thDay
8%322324346%57%
2160
16th to endDay
6%21221225%7%63%
2026
October1st to 15thDay
8%6%12425%446%53%
1800
16th to endDay
5%5%1332345%7%58%
1838
November1st to 15thDay
442332435%8%56%
1718
16th to endDay
2424425%45%7%56%
1596
December1st to 15thDay
36%345%345%6%8%48%
1560
16th to endDay
46%35%3135%5%8%50%
1664
January1st to 15thNight
35%25%5%35%5%6%7%50%
2716
16th to endNight
25%36%423347%54%
2825
February1st to 15thNight
47%36%435%5%5%7%46%
2440
16th to endNight
38%37%5%245%47%47%
1897
March1st to 15thNight
46%244245%5%7%52%
2110
16th to endNight
8%7%35%42445%9%44%
2022
April1st to 15thNight
9%6%26%5%2446%8%45%
1798
16th to endNight
15%7%24425%448%41%
1793
May1st to 15thNight
12%5%133236%48%48%
1482
16th to endNight
11%3234346%6%9%44%
1497
June1st to 15thNight
6%4332345%10%53%
1440
16th to endNight
1112213347%69%
1440
July1st to 15thNight
42123245%6%8%58%
1440
16th to endNight
42221345%8%64%
1512
August1st to 15thNight
221232448%9%58%
1571
16th to endNight
332242345%7%61%
1910
September1st to 15thNight
6%423313346%58%
1800
16th to endNight
8%212322235%65%
1932
October1st to 15thNight
11%6%23323346%51%
2160
16th to endNight
45%2432235%6%56%
2373
November1st to 15thNight
441432445%7%55%
2470
16th to endNight
36%23324447%57%
2694
December1st to 15thNight
37%25%5%245%5%7%49%
2730
16th to endNight
47%35%42445%8%48%
2912

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
15%35%425%5%6%8%50%
1552
16th to endDay
37%24424347%54%
1762
February1st to 15thDay
49%44425%46%7%45%
1683
16th to endDay
310%35%41445%8%46%
1577
March1st to 15thDay
46%15%32345%7%54%
1836
16th to endDay
7%6%345%25%46%8%46%
2202
April1st to 15thDay
9%7%3442346%9%45%
2150
16th to endDay
13%9%25%5%35%5%5%8%37%
2166
May1st to 15thDay
12%6%244345%6%8%41%
2468
16th to endDay
12%4245%35%6%7%9%38%
2616
June1st to 15thDay
7%4134346%6%10%48%
2520
16th to endDay
21222345%8%65%
2520
July1st to 15thDay
423425%5%6%9%55%
2520
16th to endDay
42134245%6%9%55%
2656
August1st to 15thDay
3214435%5%7%9%53%
2385
16th to endDay
5%2332445%6%60%
2292
September1st to 15thDay
8%41332335%7%57%
2160
16th to endDay
6%312312247%63%
2026
October1st to 15thDay
9%5%13433446%53%
1800
16th to endDay
5%5%1321345%7%57%
1838
November1st to 15thDay
442333435%8%56%
1718
16th to endDay
25%244245%5%7%55%
1596
December1st to 15thDay
35%345%345%7%8%47%
1560
16th to endDay
46%35%41346%8%50%
1664
January1st to 15thNight
35%35%5%35%5%6%7%49%
2716
16th to endNight
36%26%423447%54%
2825
February1st to 15thNight
48%36%4345%47%46%
2433
16th to endNight
38%37%4345%5%7%47%
1897
March1st to 15thNight
46%234245%5%7%51%
2123
16th to endNight
8%7%35%43445%9%44%
2022
April1st to 15thNight
9%6%35%5%3346%7%44%
1798
16th to endNight
15%7%2442445%7%41%
1793
May1st to 15thNight
12%6%133135%5%8%48%
1481
16th to endNight
11%3233346%6%9%45%
1497
June1st to 15thNight
7%41232445%10%53%
1440
16th to endNight
111221335%6%69%
1440
July1st to 15thNight
3212315%5%6%8%58%
1440
16th to endNight
32231345%8%63%
1512
August1st to 15thNight
21133235%7%10%58%
1571
16th to endNight
4313323447%61%
1910
September1st to 15thNight
6%5%23312347%57%
1800
16th to endNight
8%21232234465%
1932
October1st to 15thNight
12%6%14313346%51%
2160
16th to endNight
5%6%2432235%6%56%
2373
November1st to 15thNight
45%1442435%7%55%
2470
16th to endNight
35%2332445%7%56%
2694
December1st to 15thNight
37%25%6%2446%6%49%
2730
16th to endNight
47%35%42445%8%47%
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
29%422%29%11%1
1553
16th to endDay
29%319%29%14%2
1762
February1st to 15thDay
35%5%21%26%8%2
1683
16th to endDay
35%416%27%11%4
1577
March1st to 15thDay
27%315%33%16%2
1836
16th to endDay
33%6%14%29%12%2
2202
April1st to 15thDay
35%415%26%13%3
2150
16th to endDay
44%415%22%12%1
2166
May1st to 15thDay
38%5%14%25%13%1
2468
16th to endDay
39%6%16%23%11%2
2620
June1st to 15thDay
28%6%15%26%17%6%
2520
16th to endDay
15%310%25%30%14%
2520
July1st to 15thDay
23%6%10%21%23%15%
2371
16th to endDay
22%49%23%22%17%
2489
August1st to 15thDay
24%5%11%23%21%13%
2369
16th to endDay
22%37%22%27%17%
2292
September1st to 15thDay
26%46%19%27%15%
2160
16th to endDay
21%36%33%27%7%
2026
October1st to 15thDay
31%5%10%28%19%5%
1800
16th to endDay
24%313%32%18%7%
1838
November1st to 15thDay
26%414%26%22%6%
1718
16th to endDay
25%415%31%20%2
1596
December1st to 15thDay
32%5%23%25%12%1
1560
16th to endDay
30%420%29%12%1
1664
January1st to 15thNight
30%6%17%28%14%2
2716
16th to endNight
29%315%31%16%3
2825
February1st to 15thNight
35%6%19%26%9%2
2444
16th to endNight
35%414%25%16%3
1897
March1st to 15thNight
29%5%14%27%17%5%
2123
16th to endNight
36%414%28%13%2
2022
April1st to 15thNight
35%5%14%25%14%4
1798
16th to endNight
41%413%24%14%1
1793
May1st to 15thNight
33%5%14%26%17%1
1482
16th to endNight
33%7%18%23%14%1
1498
June1st to 15thNight
25%5%20%26%17%4
1440
16th to endNight
15%212%29%26%13%
1440
July1st to 15thNight
21%5%12%26%21%13%
1360
16th to endNight
18%211%26%23%17%
1416
August1st to 15thNight
19%412%32%19%12%
1563
16th to endNight
21%37%22%26%17%
1910
September1st to 15thNight
26%37%24%24%13%
1800
16th to endNight
22%26%30%27%10%
1932
October1st to 15thNight
33%311%23%22%5%
2160
16th to endNight
26%312%29%19%8%
2373
November1st to 15thNight
27%414%25%21%6%
2470
16th to endNight
25%5%12%32%19%4
2694
December1st to 15thNight
32%419%28%12%2
2730
16th to endNight
33%5%17%28%13%2
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
5%11%27%28%19%7%
135
16th to endDay
9%14%41%20%12%
144
February1st to 15thDay
9%22%45%19%3
126
16th to endDay
8%24%38%18%9%
81
March1st to 15thDay
10%16%37%28%6%
126
16th to endDay
16%18%36%20%8%
288
April1st to 15thDay
14%18%39%18%8%
269
16th to endDay
25%15%28%19%9%2
276
May1st to 15thDay
17%7%29%24%17%3
468
16th to endDay
19%9%25%27%15%3
517
June1st to 15thDay
8%8%27%29%19%6%
495
16th to endDay
36%31%33%22%1
495
July1st to 15thDay
5%418%38%26%6%
475
16th to endDay
4122%41%24%4
515
August1st to 15thDay
5%327%35%24%3
366
16th to endDay
6%425%31%23%9%
332
September1st to 15thDay
7%7%28%33%19%3
315
16th to endDay
10%332%25%19%7%
189
October1st to 15thDay
11%8%24%33%17%4
135
16th to endDay
10%13%36%23%13%2
144
November1st to 15thDay
48%31%34%11%9%
135
16th to endDay
14%15%37%29%3
135
December1st to 15thDay
8%22%38%20%8%
135
16th to endDay
6%15%39%27%8%2
144
January1st to 15thNight
6%20%33%26%11%1
975
16th to endNight
6%18%40%26%7%
953
February1st to 15thNight
7%15%36%30%8%
752
16th to endNight
8%15%37%28%9%
632
March1st to 15thNight
8%12%39%30%8%
720
16th to endNight
11%11%35%34%7%
678
April1st to 15thNight
12%9%39%31%6%
539
16th to endNight
18%10%28%32%9%
540
May1st to 15thNight
15%5%29%35%12%2
540
16th to endNight
12%6%29%36%14%
563
June1st to 15thNight
9%7%31%36%13%
540
16th to endNight
2337%43%12%
540
July1st to 15thNight
4227%44%21%
510
16th to endNight
4124%47%20%1
564
August1st to 15thNight
3223%48%20%
539
16th to endNight
5%220%47%23%
573
September1st to 15thNight
10%223%39%21%2
540
16th to endNight
8%327%39%18%2
543
October1st to 15thNight
15%6%28%33%14%2
720
16th to endNight
8%8%35%33%12%1
837
November1st to 15thNight
8%11%34%32%12%
950
16th to endNight
6%13%42%30%6%
975
December1st to 15thNight
7%16%39%29%6%
975
16th to endNight
8%18%36%28%7%
1040
Page generated at 2018-02-13 18:46:02. Version ac04

Copyright 2018 A. Danko


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