Herron Observing Field
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Herron Observing Field clear sky chart from 2005-11-05 to 2017-04-24.

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
47%
15025
24%
45591
16%
14984
56%
14984
29%
27708

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
24%
720
23%
2327
9%
716
41%
716
21%
1441
January16th to endNight
26%
768
25%
2443
11%
768
43%
768
21%
1536
February1st to 15thNight
29%
702
26%
2112
10%
701
45%
701
26%
1282
February16th to endNight
24%
631
25%
1893
9%
631
39%
631
24%
1185
March1st to 15thNight
29%
720
23%
2070
11%
720
40%
720
26%
1309
March16th to endNight
39%
768
22%
2112
13%
768
45%
768
31%
1303
April1st to 15thNight
42%
623
26%
1881
16%
623
53%
623
32%
1071
April16th to endNight
49%
522
26%
1653
17%
522
58%
522
33%
942
May1st to 15thNight
50%
495
22%
1485
13%
495
58%
495
30%
907
May16th to endNight
64%
513
20%
1538
13%
513
69%
513
35%
901
June1st to 15thNight
72%
495
18%
1485
16%
495
74%
495
32%
901
June16th to endNight
78%
495
18%
1485
15%
495
80%
495
38%
845
July1st to 15thNight
68%
465
15%
1395
14%
465
69%
465
28%
905
July16th to endNight
72%
522
16%
1469
15%
489
74%
489
30%
928
August1st to 15thNight
75%
494
21%
1508
22%
491
75%
491
31%
918
August16th to endNight
62%
525
18%
1750
20%
525
64%
525
22%
1155
September1st to 15thNight
64%
638
20%
1793
19%
638
65%
638
29%
1182
September16th to endNight
58%
657
24%
1815
17%
657
64%
657
31%
1152
October1st to 15thNight
54%
660
35%
1816
26%
660
61%
660
40%
1048
October16th to endNight
52%
704
34%
2112
26%
704
64%
704
38%
1161
November1st to 15thNight
49%
700
31%
2273
25%
700
61%
700
35%
1211
November16th to endNight
38%
720
28%
2340
17%
720
52%
720
29%
1347
December1st to 15thNight
31%
720
24%
2340
14%
720
45%
720
25%
1419
December16th to endNight
30%
768
20%
2496
13%
768
40%
768
19%
1659

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%5%245%35%5%6%7%40%
46005
Night
12%5%2442445%7%45%
45790
TransparencyDay
40%411%21%17%4
45706
Night
37%410%21%20%6%
45593
SeeingDay
16%6%18%22%21%13%
4779
Night
15%8%21%28%21%4
15029

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
18%7%34224345%41%
1611
16th to endDay
19%6%23323446%43%
1779
February1st to 15thDay
16%7%24324448%41%
1750
16th to endDay
20%5%24424345%41%
1580
March1st to 15thDay
16%6%25%42445%6%40%
1888
16th to endDay
17%4245%34447%41%
2111
April1st to 15thDay
12%6%25%42345%6%44%
2076
16th to endDay
11%3244345%47%47%
2165
May1st to 15thDay
11%5%25%5%35%5%6%8%41%
2136
16th to endDay
10%425%5%346%6%9%41%
2223
June1st to 15thDay
8%426%6%36%6%8%11%35%
2145
16th to endDay
4214447%6%8%12%43%
2145
July1st to 15thDay
11%5%26%7%5%8%7%7%10%28%
2145
16th to endDay
8%5%36%7%48%9%8%9%29%
2283
August1st to 15thDay
8%5%25%6%5%6%7%8%10%33%
2108
16th to endDay
12%6%36%8%5%6%7%7%8%25%
2100
September1st to 15thDay
12%7%35%5%346%6%8%35%
1823
16th to endDay
16%6%134245%6%6%42%
1815
October1st to 15thDay
13%5%13323236%54%
1812
16th to endDay
13%32432224358%
1760
November1st to 15thDay
14%413312345%55%
1582
16th to endDay
15%5%14424345%48%
1620
December1st to 15thDay
19%6%26%42345%5%40%
1620
16th to endDay
26%7%3432433435%
1728
January1st to 15thNight
19%6%34323346%42%
2327
16th to endNight
17%7%34323345%42%
2443
February1st to 15thNight
15%5%24324346%47%
2103
16th to endNight
17%5%25%414445%44%
1893
March1st to 15thNight
14%6%24424346%45%
2070
16th to endNight
12%5%24424446%47%
2112
April1st to 15thNight
12%41332345%7%49%
1881
16th to endNight
9%5%23425%448%48%
1653
May1st to 15thNight
9%424436%5%5%7%44%
1484
16th to endNight
6%4245%35%47%9%47%
1538
June1st to 15thNight
5%3245%46%6%8%11%41%
1485
16th to endNight
3214435%6%8%13%45%
1485
July1st to 15thNight
6%426%6%46%6%7%11%35%
1485
16th to endNight
5%426%6%27%7%7%11%37%
1577
August1st to 15thNight
5%425%5%25%6%6%12%42%
1519
16th to endNight
11%6%26%7%35%5%6%10%34%
1750
September1st to 15thNight
9%5%26%5%36%5%6%9%38%
1793
16th to endNight
14%4145%3445%6%45%
1815
October1st to 15thNight
10%5%23313337%55%
1816
16th to endNight
10%42332333458%
2112
November1st to 15thNight
11%5%13313236%57%
2273
16th to endNight
15%6%23323345%50%
2340
December1st to 15thNight
15%7%25%423347%43%
2340
16th to endNight
22%7%25%423346%35%
2496

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%38%16%23%4
1612
16th to endDay
43%26%20%21%6%
1779
February1st to 15thDay
40%27%22%22%3
1752
16th to endDay
44%26%20%19%5%
1580
March1st to 15thDay
43%38%19%19%5%
1888
16th to endDay
41%312%23%16%3
2112
April1st to 15thDay
38%210%22%20%4
2076
16th to endDay
34%48%25%22%4
2165
May1st to 15thDay
39%414%21%17%2
2136
16th to endDay
36%5%15%25%14%2
2227
June1st to 15thDay
38%6%18%26%8%1
2145
16th to endDay
27%6%17%29%15%2
2145
July1st to 15thDay
42%8%19%19%8%1
2006
16th to endDay
41%9%19%20%8%1
2128
August1st to 15thDay
38%8%17%23%9%1
2095
16th to endDay
50%6%14%17%9%1
2100
September1st to 15thDay
42%5%14%19%14%3
1823
16th to endDay
40%410%18%20%4
1815
October1st to 15thDay
32%29%19%26%9%
1812
16th to endDay
31%15%19%31%10%
1760
November1st to 15thDay
32%25%16%33%9%
1582
16th to endDay
38%35%17%27%7%
1620
December1st to 15thDay
45%28%21%15%7%
1620
16th to endDay
52%27%17%14%5%
1728
January1st to 15thNight
42%27%19%23%5%
2327
16th to endNight
43%15%20%22%6%
2443
February1st to 15thNight
39%16%21%21%8%
2112
16th to endNight
41%2421%24%5%
1893
March1st to 15thNight
39%39%20%18%8%
2070
16th to endNight
36%310%26%18%4
2112
April1st to 15thNight
33%29%24%23%6%
1881
16th to endNight
33%39%24%20%8%
1653
May1st to 15thNight
36%414%22%19%2
1485
16th to endNight
31%5%16%27%14%3
1540
June1st to 15thNight
32%8%21%26%10%1
1485
16th to endNight
27%7%20%24%17%3
1485
July1st to 15thNight
38%7%19%22%9%2
1395
16th to endNight
35%9%21%20%11%1
1469
August1st to 15thNight
32%9%15%27%13%1
1508
16th to endNight
43%7%17%16%13%1
1750
September1st to 15thNight
40%5%15%19%13%4
1793
16th to endNight
38%410%21%18%5%
1815
October1st to 15thNight
31%210%18%28%8%
1816
16th to endNight
30%2418%32%13%
2112
November1st to 15thNight
30%2416%32%12%
2273
16th to endNight
36%25%18%27%9%
2340
December1st to 15thNight
40%29%21%18%7%
2340
16th to endNight
49%28%17%18%4
2496

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
25%12%41%14%6%
90
16th to endDay
22%29%39%44
96
February1st to 15thDay
24%22%37%13%2
90
16th to endDay
30%14%43%11%
81
March1st to 15thDay
24%14%32%20%6%1
178
16th to endDay
18%10%33%23%12%2
288
April1st to 15thDay
19%10%30%21%17%2
270
16th to endDay
14%422%30%23%4
243
May1st to 15thDay
13%7%25%21%18%12%
228
16th to endDay
14%211%29%25%15%
267
June1st to 15thDay
11%17%26%25%27%
255
16th to endDay
310%25%25%34%
255
July1st to 15thDay
11%8%21%28%28%
245
16th to endDay
10%2312%38%32%
270
August1st to 15thDay
15%1320%32%26%
253
16th to endDay
16%2423%30%22%
268
September1st to 15thDay
14%5%6%21%29%23%
255
16th to endDay
20%311%31%24%9%
254
October1st to 15thDay
18%223%24%25%5%
255
16th to endDay
15%5%19%23%27%6%
272
November1st to 15thDay
30%15%20%18%13%2
90
16th to endDay
12%12%36%23%13%2
90
December1st to 15thDay
26%15%34%21%2
90
16th to endDay
37%12%34%12%3
96
January1st to 15thNight
24%15%30%22%7%
720
16th to endNight
22%16%30%27%4
768
February1st to 15thNight
20%14%32%28%4
704
16th to endNight
19%17%34%24%3
631
March1st to 15thNight
18%13%35%25%6%
720
16th to endNight
16%10%28%31%13%
768
April1st to 15thNight
15%10%28%28%16%
623
16th to endNight
13%6%26%32%19%1
522
May1st to 15thNight
10%7%23%31%24%2
495
16th to endNight
9%214%31%34%7%
515
June1st to 15thNight
6%28%34%37%10%
495
16th to endNight
417%34%40%13%
495
July1st to 15thNight
7%35%23%47%12%
465
16th to endNight
43419%53%14%
522
August1st to 15thNight
7%2427%46%11%
494
16th to endNight
14%26%24%42%10%
525
September1st to 15thNight
12%27%24%42%10%
638
16th to endNight
16%114%34%29%3
657
October1st to 15thNight
14%421%29%23%5%
660
16th to endNight
12%7%22%32%20%4
704
November1st to 15thNight
14%7%24%29%22%2
700
16th to endNight
19%12%26%26%14%
720
December1st to 15thNight
18%12%30%27%10%
720
16th to endNight
26%11%27%26%7%
768
Page generated at 2017-04-25 07:48:17. Version ac04

Copyright 2017 A. Danko


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