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 2017-09-22.

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
38%
16144
17%
46609
9%
16097
45%
16097
26%
30540

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
30%
900
14%
2506
7%
895
35%
895
21%
1787
January16th to endNight
28%
960
13%
2503
5%
960
33%
960
19%
1842
February1st to 15thNight
31%
879
13%
2288
4%
875
38%
875
25%
1604
February16th to endNight
33%
783
16%
2045
6%
783
41%
783
26%
1401
March1st to 15thNight
33%
541
15%
1981
11%
541
39%
541
20%
1275
March16th to endNight
33%
576
15%
2112
12%
576
40%
576
16%
1420
April1st to 15thNight
33%
539
19%
1812
15%
539
43%
539
23%
1167
April16th to endNight
29%
540
17%
1629
12%
540
39%
540
18%
1174
May1st to 15thNight
33%
540
14%
1536
8%
540
38%
540
24%
1036
May16th to endNight
42%
563
16%
1498
6%
561
47%
561
32%
952
June1st to 15thNight
48%
540
13%
1404
5%
540
52%
540
37%
871
June16th to endNight
56%
540
18%
1260
7%
540
60%
540
48%
767
July1st to 15thNight
61%
510
17%
1237
7%
510
63%
510
50%
722
July16th to endNight
66%
564
22%
1480
12%
531
69%
531
49%
785
August1st to 15thNight
66%
539
21%
1610
19%
536
70%
536
38%
915
August16th to endNight
60%
573
23%
1763
20%
573
67%
573
40%
955
September1st to 15thNight
59%
540
24%
1800
22%
540
67%
540
38%
947
September16th to endNight
44%
529
24%
1907
17%
529
55%
529
31%
1046
October1st to 15thNight
36%
660
24%
1980
15%
660
44%
660
32%
1179
October16th to endNight
35%
704
17%
2112
9%
704
42%
704
23%
1404
November1st to 15thNight
34%
864
21%
2418
9%
864
43%
864
27%
1555
November16th to endNight
28%
900
16%
2520
9%
900
35%
900
22%
1758
December1st to 15thNight
27%
900
11%
2520
4%
900
33%
900
18%
1863
December16th to endNight
22%
960
12%
2688
4%
960
30%
960
13%
2115

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%7%36%5%3445%7%38%
48279
Night
11%8%35%5%2445%6%42%
46777
Cloud CoverDay
13%7%36%5%3445%7%37%
48290
Night
11%8%35%5%2445%6%42%
46781
Cloud CoverDay
13%7%36%5%3445%7%37%
48288
Night
11%8%35%5%2445%6%41%
46781
TransparencyDay
45%5%14%23%9%
47965
Night
42%414%24%12%1
46609
SeeingDay
17%6%28%29%14%3
6144
Night
16%7%31%32%11%1
16145

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
8%11%6%9%7%46%6%47%26%
1432
16th to endDay
8%14%48%7%46%6%5%7%25%
1719
February1st to 15thDay
8%12%5%8%7%35%46%6%30%
1575
16th to endDay
10%9%49%8%36%6%48%27%
1437
March1st to 15thDay
14%10%47%6%34447%32%
1969
16th to endDay
16%8%47%6%34448%31%
2112
April1st to 15thDay
16%8%36%42435%6%37%
2136
16th to endDay
24%11%35%424335%29%
2328
May1st to 15thDay
20%6%35%6%3445%6%33%
2415
16th to endDay
15%5%26%5%35%5%5%9%35%
2617
June1st to 15thDay
15%5%35%425%5%6%8%37%
2552
16th to endDay
8%5%244345%6%9%45%
2700
July1st to 15thDay
7%31333346%8%53%
2646
16th to endDay
5%3144245%6%8%52%
2586
August1st to 15thDay
9%425%6%46%5%7%8%40%
2340
16th to endDay
12%32442445%7%48%
2438
September1st to 15thDay
10%424433447%48%
2157
16th to endDay
16%5%2441445%6%44%
1854
October1st to 15thDay
15%7%25%5%23246%44%
1650
16th to endDay
18%9%26%323346%37%
1760
November1st to 15thDay
11%10%46%5%23446%40%
1440
16th to endDay
15%9%36%5%35%36%8%32%
1440
December1st to 15thDay
14%12%5%8%9%45%446%25%
1440
16th to endDay
18%16%6%10%6%24345%22%
1536
January1st to 15thNight
8%8%5%8%7%46%5%6%7%32%
2506
16th to endNight
10%13%5%8%6%35%46%7%29%
2503
February1st to 15thNight
8%12%46%6%34446%37%
2285
16th to endNight
7%7%37%7%35%5%6%7%38%
2045
March1st to 15thNight
12%8%37%5%34346%40%
1969
16th to endNight
14%10%46%6%23445%35%
2112
April1st to 15thNight
15%9%35%4235%5%6%39%
1812
16th to endNight
21%9%36%5%2434434%
1629
May1st to 15thNight
17%7%245%3335%7%39%
1536
16th to endNight
12%5%2442346%8%44%
1496
June1st to 15thNight
12%314415%36%8%48%
1404
16th to endNight
6%31332445%6%56%
1260
July1st to 15thNight
221432446%7%58%
1311
16th to endNight
421332345%8%59%
1581
August1st to 15thNight
7%31343445%7%53%
1620
16th to endNight
8%32421435%5%58%
1763
September1st to 15thNight
8%41333345%6%57%
1800
16th to endNight
10%5%14423446%52%
1907
October1st to 15thNight
14%6%24313246%50%
1980
16th to endNight
19%9%24313336%40%
2112
November1st to 15thNight
13%7%26%43335%5%45%
2418
16th to endNight
13%10%45%5%24446%37%
2520
December1st to 15thNight
11%11%5%7%7%35%446%31%
2520
16th to endNight
17%13%5%8%6%2445%5%23%
2688

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
8%12%5%9%7%46%5%47%26%
1432
16th to endDay
8%14%48%7%46%6%5%7%25%
1719
February1st to 15thDay
8%12%5%8%7%36%46%6%30%
1575
16th to endDay
9%9%410%8%36%5%48%27%
1437
March1st to 15thDay
14%10%47%5%3445%7%32%
1980
16th to endDay
15%9%47%6%35%448%30%
2112
April1st to 15thDay
16%8%36%5%2435%5%37%
2136
16th to endDay
24%11%35%434335%29%
2328
May1st to 15thDay
20%6%35%5%3445%6%32%
2415
16th to endDay
15%6%26%5%35%45%8%36%
2617
June1st to 15thDay
15%5%35%425%5%6%7%37%
2552
16th to endDay
8%5%144345%6%9%45%
2700
July1st to 15thDay
7%31333445%9%53%
2646
16th to endDay
5%31342446%8%52%
2586
August1st to 15thDay
9%425%5%45%5%6%8%40%
2340
16th to endDay
11%32442445%7%48%
2438
September1st to 15thDay
11%424434447%49%
2157
16th to endDay
15%5%24324447%44%
1854
October1st to 15thDay
15%7%26%433346%44%
1650
16th to endDay
18%9%26%323445%37%
1760
November1st to 15thDay
11%10%37%5%33446%40%
1440
16th to endDay
15%9%26%5%35%37%8%32%
1440
December1st to 15thDay
13%12%5%8%9%45%445%25%
1440
16th to endDay
18%16%6%9%6%23345%22%
1536
January1st to 15thNight
8%8%5%8%7%46%46%7%32%
2506
16th to endNight
10%13%5%8%5%35%46%6%30%
2503
February1st to 15thNight
8%12%46%6%34347%37%
2278
16th to endNight
7%8%37%6%35%5%5%7%38%
2045
March1st to 15thNight
11%9%37%5%24346%40%
1981
16th to endNight
14%10%46%6%23445%35%
2112
April1st to 15thNight
15%8%3442345%6%40%
1812
16th to endNight
21%8%35%5%2334434%
1629
May1st to 15thNight
17%7%2443345%7%40%
1535
16th to endNight
12%5%25%42346%9%43%
1496
June1st to 15thNight
12%31342435%9%48%
1404
16th to endNight
6%22332345%7%56%
1260
July1st to 15thNight
231432447%7%58%
1311
16th to endNight
421332345%8%59%
1581
August1st to 15thNight
7%31343445%7%53%
1620
16th to endNight
8%314313446%58%
1763
September1st to 15thNight
8%41333345%6%57%
1800
16th to endNight
10%5%14423446%52%
1907
October1st to 15thNight
14%6%33323246%49%
1980
16th to endNight
19%9%25%313336%40%
2112
November1st to 15thNight
13%6%25%5%2335%5%44%
2418
16th to endNight
13%10%45%5%24446%38%
2520
December1st to 15thNight
12%11%47%7%34446%31%
2520
16th to endNight
17%13%5%8%7%25%45%5%23%
2688

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
8%11%5%9%8%46%6%47%26%
1432
16th to endDay
8%13%5%8%7%46%5%5%8%25%
1719
February1st to 15thDay
8%12%5%8%7%36%45%7%30%
1575
16th to endDay
10%9%5%9%8%35%5%5%7%27%
1437
March1st to 15thDay
14%10%47%6%24447%32%
1980
16th to endDay
15%9%37%6%44447%31%
2110
April1st to 15thDay
16%8%36%42435%6%37%
2136
16th to endDay
24%12%35%433435%29%
2328
May1st to 15thDay
20%6%35%5%34446%33%
2415
16th to endDay
15%6%26%5%35%45%9%35%
2617
June1st to 15thDay
14%5%35%425%5%6%7%37%
2552
16th to endDay
8%5%245%25%5%6%9%45%
2700
July1st to 15thDay
7%3134245%6%9%52%
2646
16th to endDay
5%4134245%6%10%51%
2586
August1st to 15thDay
9%425%5%46%6%6%8%40%
2340
16th to endDay
11%42442445%7%48%
2438
September1st to 15thDay
10%4244235%47%48%
2157
16th to endDay
16%5%23425%35%6%44%
1854
October1st to 15thDay
15%8%25%423246%43%
1650
16th to endDay
18%9%26%42335%5%37%
1760
November1st to 15thDay
11%10%36%5%33446%40%
1440
16th to endDay
15%9%26%5%25%46%9%32%
1440
December1st to 15thDay
13%11%5%8%9%5%4436%25%
1440
16th to endDay
18%15%7%10%5%33335%22%
1536
January1st to 15thNight
8%8%5%8%7%46%46%7%32%
2506
16th to endNight
10%13%5%8%6%35%46%7%29%
2503
February1st to 15thNight
8%12%46%6%34446%37%
2278
16th to endNight
7%8%37%6%35%5%6%7%38%
2045
March1st to 15thNight
12%9%27%5%24346%40%
1981
16th to endNight
14%10%46%6%23446%35%
2112
April1st to 15thNight
15%8%35%4235%5%6%40%
1812
16th to endNight
21%9%35%5%2334434%
1629
May1st to 15thNight
17%7%245%2335%7%39%
1535
16th to endNight
12%5%243325%7%8%44%
1496
June1st to 15thNight
12%31342435%9%48%
1404
16th to endNight
6%31342445%7%56%
1260
July1st to 15thNight
321432446%8%57%
1311
16th to endNight
431332435%8%59%
1581
August1st to 15thNight
7%32342445%7%53%
1620
16th to endNight
8%323313445%58%
1763
September1st to 15thNight
8%31233345%6%57%
1800
16th to endNight
11%414423447%51%
1907
October1st to 15thNight
14%6%24323236%49%
1980
16th to endNight
19%9%25%323346%40%
2112
November1st to 15thNight
12%7%35%5%3335%5%44%
2418
16th to endNight
12%10%45%5%2345%5%38%
2520
December1st to 15thNight
12%11%47%7%44446%31%
2520
16th to endNight
17%13%5%8%7%2445%6%23%
2688

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
55%5%11%18%8%
1433
16th to endDay
56%5%15%18%4
1719
February1st to 15thDay
53%416%18%6%
1576
16th to endDay
53%6%12%19%6%
1437
March1st to 15thDay
51%5%15%20%6%
1980
16th to endDay
51%5%15%24%3
2112
April1st to 15thDay
47%312%23%11%1
2136
16th to endDay
57%312%17%7%1
2328
May1st to 15thDay
52%413%21%7%
2415
16th to endDay
45%6%14%23%10%
2621
June1st to 15thDay
43%5%16%25%8%
2552
16th to endDay
33%6%18%28%11%1
2700
July1st to 15thDay
27%6%16%30%16%2
2491
16th to endDay
28%6%18%28%16%2
2424
August1st to 15thDay
38%7%14%27%9%2
2326
16th to endDay
33%5%16%28%13%1
2438
September1st to 15thDay
34%5%14%32%12%
2157
16th to endDay
39%5%12%31%9%
1854
October1st to 15thDay
42%313%25%13%1
1650
16th to endDay
47%415%22%8%
1760
November1st to 15thDay
44%413%22%14%1
1440
16th to endDay
48%5%20%17%7%
1440
December1st to 15thDay
60%412%15%6%
1440
16th to endDay
64%310%15%5%
1536
January1st to 15thNight
49%6%12%22%9%
2506
16th to endNight
53%315%19%6%
2503
February1st to 15thNight
47%317%21%10%
2288
16th to endNight
43%414%23%11%
2045
March1st to 15thNight
46%415%23%9%
1981
16th to endNight
50%413%26%4
2112
April1st to 15thNight
44%410%26%12%1
1812
16th to endNight
53%47%18%13%2
1629
May1st to 15thNight
43%5%13%22%12%1
1536
16th to endNight
36%5%15%25%15%1
1498
June1st to 15thNight
33%416%30%13%1
1404
16th to endNight
26%414%31%18%3
1260
July1st to 15thNight
23%417%33%18%2
1237
16th to endNight
21%5%16%34%16%4
1480
August1st to 15thNight
28%6%13%31%16%3
1610
16th to endNight
26%5%16%30%17%3
1763
September1st to 15thNight
27%414%32%20%
1800
16th to endNight
32%412%35%13%1
1907
October1st to 15thNight
36%211%28%16%3
1980
16th to endNight
45%413%23%12%
2112
November1st to 15thNight
41%313%23%16%1
2418
16th to endNight
47%417%18%10%1
2520
December1st to 15thNight
54%5%14%19%6%
2520
16th to endNight
61%5%12%14%5%
2688

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
18%7%33%26%12%1
90
16th to endDay
22%10%31%28%7%
96
February1st to 15thDay
13%14%43%25%3
90
16th to endDay
19%13%28%30%6%1
81
March1st to 15thDay
25%7%37%27%1
90
16th to endDay
25%5%35%26%8%
96
April1st to 15thDay
20%12%30%24%9%1
255
16th to endDay
30%8%29%22%7%1
438
May1st to 15thDay
24%10%30%23%9%1
468
16th to endDay
21%5%33%23%12%2
517
June1st to 15thDay
14%5%29%31%15%2
495
16th to endDay
10%434%32%13%3
495
July1st to 15thDay
8%425%33%20%6%
475
16th to endDay
8%322%37%25%3
515
August1st to 15thDay
11%121%35%25%4
493
16th to endDay
15%121%33%20%6%
478
September1st to 15thDay
13%224%36%16%6%
312
16th to endDay
27%225%26%8%9%
108
October1st to 15thDay
7%10%36%28%10%6%
90
16th to endDay
23%7%34%18%15%
96
November1st to 15thDay
27%28%42%16%2
90
16th to endDay
38%7%30%17%5%
90
December1st to 15thDay
18%12%30%34%4
90
16th to endDay
34%12%35%14%3
96
January1st to 15thNight
12%10%36%29%9%1
900
16th to endNight
18%9%35%31%5%
960
February1st to 15thNight
15%9%33%32%7%1
880
16th to endNight
12%8%38%29%10%1
783
March1st to 15thNight
16%7%35%29%10%
541
16th to endNight
19%9%30%27%11%1
576
April1st to 15thNight
20%7%33%30%7%
539
16th to endNight
25%7%30%26%7%1
540
May1st to 15thNight
21%8%33%26%9%
540
16th to endNight
15%5%31%32%12%1
563
June1st to 15thNight
14%230%40%11%
540
16th to endNight
7%229%45%14%
540
July1st to 15thNight
4127%40%25%1
510
16th to endNight
6%122%47%20%2
564
August1st to 15thNight
9%114%45%26%2
539
16th to endNight
9%222%38%24%3
573
September1st to 15thNight
10%223%38%20%3
540
16th to endNight
12%7%32%27%17%2
529
October1st to 15thNight
18%7%32%26%12%1
660
16th to endNight
25%7%26%30%8%
704
November1st to 15thNight
16%9%34%28%11%
864
16th to endNight
18%11%34%26%8%
900
December1st to 15thNight
19%7%37%28%7%
900
16th to endNight
24%10%28%28%7%
960
Page generated at 2017-09-23 05:43:38. Version ac04

Copyright 2017 A. Danko


Hutchinson Clear Sky Chart | Charts Home