Hutchinson
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hutchinson clear sky chart from 2005-11-05 to 2017-09-24.

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%
15882
26%
47000
16%
15836
56%
15836
38%
26131

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
37%
900
29%
2327
13%
895
48%
895
40%
1367
January16th to endNight
39%
960
33%
2496
14%
960
50%
960
45%
1403
February1st to 15thNight
35%
812
22%
2220
9%
808
43%
808
33%
1372
February16th to endNight
34%
632
30%
1894
11%
632
48%
632
35%
1048
March1st to 15thNight
39%
597
25%
2037
15%
597
50%
597
32%
1107
March16th to endNight
32%
576
20%
2112
13%
576
43%
576
25%
1232
April1st to 15thNight
35%
539
22%
1906
13%
539
51%
539
29%
1056
April16th to endNight
35%
540
21%
1620
14%
540
46%
540
29%
992
May1st to 15thNight
40%
540
22%
1620
17%
540
50%
540
31%
972
May16th to endNight
49%
562
18%
1684
15%
561
56%
561
35%
978
June1st to 15thNight
53%
540
19%
1620
11%
540
60%
540
43%
852
June16th to endNight
57%
540
24%
1620
15%
540
65%
540
51%
793
July1st to 15thNight
74%
510
20%
1530
18%
510
76%
510
46%
797
July16th to endNight
72%
564
24%
1594
24%
531
75%
531
46%
838
August1st to 15thNight
75%
539
22%
1610
25%
536
77%
536
41%
876
August16th to endNight
68%
573
27%
1775
28%
573
72%
573
40%
953
September1st to 15thNight
57%
540
22%
1978
21%
540
64%
540
33%
1053
September16th to endNight
58%
519
33%
1914
29%
519
68%
519
40%
911
October1st to 15thNight
48%
560
33%
1880
25%
560
56%
560
34%
1016
October16th to endNight
49%
704
33%
2112
17%
704
60%
704
49%
1046
November1st to 15thNight
47%
875
32%
2275
13%
875
57%
875
51%
1205
November16th to endNight
43%
900
31%
2340
14%
900
53%
900
44%
1314
December1st to 15thNight
38%
900
26%
2340
11%
900
48%
900
38%
1410
December16th to endNight
38%
960
30%
2496
14%
960
49%
960
36%
1540

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
8%42442345%7%51%
47923
Night
8%424323347%54%
47196
Cloud CoverDay
8%42442445%7%51%
47921
Night
8%42332335%7%54%
47196
TransparencyDay
31%413%27%18%4
47621
Night
29%312%27%21%5%
47001
SeeingDay
10%5%25%33%20%4
5873
Night
10%6%31%37%13%
15883

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
6%5%14322247%58%
1611
16th to endDay
7%5%2431335%7%54%
1728
February1st to 15thDay
5%7%36%5%34436%49%
1651
16th to endDay
6%5%233235%47%54%
1580
March1st to 15thDay
9%5%244245%5%6%48%
1922
16th to endDay
15%6%14413346%46%
2112
April1st to 15thDay
11%5%343235%48%47%
2038
16th to endDay
15%6%25%5%23436%42%
2340
May1st to 15thDay
11%5%3333445%7%47%
2331
16th to endDay
10%6%25%5%345%6%6%43%
2430
June1st to 15thDay
6%325%42435%8%53%
2340
16th to endDay
4112335%45%9%57%
2340
July1st to 15thDay
6%3245%35%6%6%10%46%
2340
16th to endDay
5%3133245%5%10%53%
2466
August1st to 15thDay
7%4134346%6%10%48%
2340
16th to endDay
5%3244245%6%7%54%
2424
September1st to 15thDay
8%5%2442446%5%50%
1980
16th to endDay
7%314423445%57%
1904
October1st to 15thDay
14%412213335%56%
1738
16th to endDay
6%5%13323245%60%
1757
November1st to 15thDay
5%313323335%62%
1583
16th to endDay
9%41331222464%
1620
December1st to 15thDay
11%7%2441335%7%50%
1620
16th to endDay
10%8%34314345%48%
1728
January1st to 15thNight
7%5%24323345%57%
2327
16th to endNight
6%42331333461%
2496
February1st to 15thNight
10%7%25%423436%49%
2210
16th to endNight
7%5%2432445%6%54%
1894
March1st to 15thNight
6%6%2432445%7%51%
2037
16th to endNight
13%7%24323435%48%
2112
April1st to 15thNight
11%5%1442335%7%49%
1906
16th to endNight
14%6%24323346%47%
1620
May1st to 15thNight
13%423333347%48%
1619
16th to endNight
10%3234145%7%10%46%
1683
June1st to 15thNight
7%21331445%10%55%
1620
16th to endNight
311232446%9%60%
1620
July1st to 15thNight
5%11342446%9%56%
1620
16th to endNight
43133225%7%10%54%
1702
August1st to 15thNight
4214425%46%10%52%
1620
16th to endNight
5%32442345%6%57%
1775
September1st to 15thNight
6%425%5%24447%52%
1978
16th to endNight
5%31332445%6%59%
1914
October1st to 15thNight
11%414323246%55%
1880
16th to endNight
7%2321223467%
2112
November1st to 15thNight
5%322213246%64%
2275
16th to endNight
10%312322236%62%
2340
December1st to 15thNight
10%5%24324346%52%
2340
16th to endNight
10%6%34313348%49%
2496

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
6%5%14322246%58%
1611
16th to endDay
7%5%24313447%54%
1728
February1st to 15thDay
5%7%36%5%25%436%49%
1651
16th to endDay
6%5%233235%5%7%54%
1580
March1st to 15thDay
10%5%2442445%6%48%
1922
16th to endDay
15%6%1441335%6%46%
2110
April1st to 15thDay
11%5%243245%48%47%
2038
16th to endDay
15%6%25%5%23446%42%
2340
May1st to 15thDay
11%5%3442445%7%47%
2331
16th to endDay
10%6%25%5%345%5%6%43%
2430
June1st to 15thDay
7%42442436%8%53%
2340
16th to endDay
4112425%5%5%9%57%
2340
July1st to 15thDay
6%3245%35%5%6%10%46%
2340
16th to endDay
5%2134245%6%9%53%
2466
August1st to 15thDay
7%4134345%6%10%48%
2340
16th to endDay
5%3243245%5%8%54%
2424
September1st to 15thDay
8%5%24425%45%6%50%
1980
16th to endDay
7%32442345%5%57%
1904
October1st to 15thDay
14%312312345%56%
1738
16th to endDay
6%5%23313245%61%
1757
November1st to 15thDay
5%31332344462%
1583
16th to endDay
9%41341222464%
1620
December1st to 15thDay
11%7%2441335%6%50%
1620
16th to endDay
10%8%34314436%48%
1728
January1st to 15thNight
7%5%24323345%57%
2327
16th to endNight
6%42332333461%
2496
February1st to 15thNight
10%7%25%423436%49%
2210
16th to endNight
7%5%2432445%6%54%
1894
March1st to 15thNight
7%6%25%31445%7%51%
2037
16th to endNight
14%6%24324435%48%
2112
April1st to 15thNight
11%41442345%7%49%
1906
16th to endNight
14%6%24323346%47%
1620
May1st to 15thNight
13%42342335%7%48%
1619
16th to endNight
9%32341447%10%46%
1683
June1st to 15thNight
6%21331445%10%55%
1620
16th to endNight
31232446%9%60%
1620
July1st to 15thNight
42134245%6%10%55%
1620
16th to endNight
431332348%10%54%
1702
August1st to 15thNight
422443445%10%52%
1620
16th to endNight
5%31442345%6%57%
1775
September1st to 15thNight
6%425%5%24447%52%
1978
16th to endNight
5%31332345%6%59%
1914
October1st to 15thNight
11%424323245%55%
1880
16th to endNight
7%2321223467%
2112
November1st to 15thNight
5%223212246%64%
2275
16th to endNight
10%312322236%62%
2340
December1st to 15thNight
10%424324346%52%
2340
16th to endNight
10%6%34323347%49%
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
26%214%33%20%2
1612
16th to endDay
29%215%31%17%3
1728
February1st to 15thDay
36%414%27%12%3
1652
16th to endDay
28%313%29%20%4
1580
March1st to 15thDay
35%410%25%20%4
1922
16th to endDay
38%412%26%14%3
2112
April1st to 15thDay
35%313%28%15%2
2038
16th to endDay
41%311%27%12%2
2340
May1st to 15thDay
34%5%13%22%20%1
2331
16th to endDay
38%5%14%27%12%2
2434
June1st to 15thDay
28%416%26%18%5%
2340
16th to endDay
22%5%13%28%22%7%
2340
July1st to 15thDay
30%6%13%28%17%2
2201
16th to endDay
24%415%30%21%4
2311
August1st to 15thDay
28%6%18%25%15%5%
2326
16th to endDay
26%5%13%28%19%6%
2424
September1st to 15thDay
32%5%12%25%16%7%
1980
16th to endDay
27%410%31%21%4
1904
October1st to 15thDay
30%310%25%25%5%
1738
16th to endDay
26%29%29%25%6%
1757
November1st to 15thDay
24%210%26%27%8%
1583
16th to endDay
26%29%30%25%5%
1620
December1st to 15thDay
35%214%28%17%1
1620
16th to endDay
38%311%27%16%2
1728
January1st to 15thNight
29%210%29%24%3
2327
16th to endNight
26%211%30%23%4
2496
February1st to 15thNight
37%214%24%16%4
2220
16th to endNight
30%211%28%19%7%
1894
March1st to 15thNight
32%310%25%20%7%
2037
16th to endNight
38%311%25%16%3
2112
April1st to 15thNight
33%411%25%22%3
1906
16th to endNight
37%413%20%20%3
1620
May1st to 15thNight
35%413%25%18%2
1620
16th to endNight
30%6%21%27%12%2
1685
June1st to 15thNight
24%418%29%18%4
1620
16th to endNight
18%414%33%23%5%
1620
July1st to 15thNight
22%5%13%30%23%4
1530
16th to endNight
23%416%29%21%3
1594
August1st to 15thNight
25%6%16%30%15%5%
1610
16th to endNight
26%5%12%25%22%7%
1775
September1st to 15thNight
30%413%25%16%8%
1978
16th to endNight
24%310%25%29%6%
1914
October1st to 15thNight
30%39%23%24%8%
1880
16th to endNight
21%28%28%31%7%
2112
November1st to 15thNight
21%210%24%31%9%
2275
16th to endNight
26%29%29%25%7%
2340
December1st to 15thNight
32%213%28%19%2
2340
16th to endNight
34%312%27%16%5%
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
14%8%36%30%7%2
90
16th to endDay
15%9%39%28%6%1
96
February1st to 15thDay
5%14%40%33%6%
90
16th to endDay
27%49%29%7%3
81
March1st to 15thDay
15%11%41%25%5%1
90
16th to endDay
18%7%42%25%6%
96
April1st to 15thDay
11%10%39%29%8%
157
16th to endDay
18%11%37%23%8%1
450
May1st to 15thDay
13%8%33%28%12%3
468
16th to endDay
15%7%30%27%14%3
517
June1st to 15thDay
9%323%35%22%4
495
16th to endDay
5%326%41%21%2
495
July1st to 15thDay
7%312%44%27%4
475
16th to endDay
5%11%39%34%8%
515
August1st to 15thDay
9%18%38%36%6%
493
16th to endDay
6%312%40%30%6%
464
September1st to 15thDay
2117%41%30%7%
135
16th to endDay
7%224%28%21%14%
114
October1st to 15thDay
8%7%17%35%18%11%
90
16th to endDay
4340%26%17%8%
96
November1st to 15thDay
7%426%32%23%5%
90
16th to endDay
23%10%36%23%6%
90
December1st to 15thDay
10%13%43%22%8%2
90
16th to endDay
21%9%42%19%6%
96
January1st to 15thNight
9%10%36%35%7%
900
16th to endNight
8%8%39%35%7%
960
February1st to 15thNight
12%8%37%36%4
812
16th to endNight
10%10%40%33%4
632
March1st to 15thNight
10%10%37%35%7%
597
16th to endNight
16%9%39%28%6%
576
April1st to 15thNight
14%10%36%30%7%
539
16th to endNight
18%9%34%30%6%
540
May1st to 15thNight
14%7%32%32%12%1
540
16th to endNight
11%5%28%34%17%2
563
June1st to 15thNight
8%328%39%18%
540
16th to endNight
2232%44%17%
540
July1st to 15thNight
5%13%55%23%1
510
16th to endNight
6%112%47%30%1
564
August1st to 15thNight
5%17%56%28%1
539
16th to endNight
7%114%39%35%1
573
September1st to 15thNight
8%322%40%22%2
540
16th to endNight
6%326%40%21%1
519
October1st to 15thNight
16%427%31%18%1
560
16th to endNight
9%5%33%37%13%
704
November1st to 15thNight
7%7%33%35%15%
875
16th to endNight
12%9%32%35%9%
900
December1st to 15thNight
13%8%36%34%6%
900
16th to endNight
13%7%34%36%7%
960
Page generated at 2017-09-25 08:02:16. Version ac04

Copyright 2017 A. Danko


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