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 2019-07-16.

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
46%
18343
26%
54243
16%
18297
55%
18297
38%
30276

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
38%
1050
29%
2717
13%
1045
48%
1045
39%
1621
January16th to endNight
38%
1120
33%
2912
13%
1120
50%
1120
47%
1616
February1st to 15thNight
33%
950
23%
2598
9%
946
42%
946
32%
1609
February16th to endNight
33%
736
27%
2206
10%
736
46%
736
33%
1262
March1st to 15thNight
37%
697
26%
2377
16%
697
49%
697
32%
1282
March16th to endNight
33%
672
20%
2464
13%
672
44%
672
25%
1434
April1st to 15thNight
35%
629
23%
2225
14%
629
50%
629
29%
1231
April16th to endNight
35%
624
21%
1871
14%
624
46%
624
30%
1133
May1st to 15thNight
40%
630
21%
1890
16%
630
49%
630
30%
1148
May16th to endNight
49%
658
18%
1972
15%
657
55%
657
35%
1143
June1st to 15thNight
54%
630
21%
1890
12%
630
62%
630
45%
978
June16th to endNight
56%
630
23%
1890
15%
630
64%
630
52%
926
July1st to 15thNight
75%
600
21%
1800
20%
600
77%
600
47%
925
July16th to endNight
72%
615
23%
1747
23%
582
75%
582
45%
922
August1st to 15thNight
73%
575
23%
1717
25%
572
77%
572
41%
932
August16th to endNight
66%
621
26%
1924
27%
621
70%
621
41%
1027
September1st to 15thNight
56%
585
23%
2143
23%
585
63%
585
31%
1162
September16th to endNight
59%
582
31%
2145
28%
582
68%
582
40%
1032
October1st to 15thNight
44%
662
30%
2222
22%
662
53%
662
31%
1237
October16th to endNight
48%
832
34%
2496
18%
832
60%
832
49%
1235
November1st to 15thNight
45%
1025
31%
2665
13%
1025
55%
1025
47%
1455
November16th to endNight
45%
1050
31%
2730
14%
1050
54%
1050
45%
1531
December1st to 15thNight
39%
1050
27%
2730
13%
1050
49%
1050
39%
1621
December16th to endNight
36%
1120
29%
2912
13%
1120
48%
1120
35%
1814

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%5%2442345%7%51%
55068
Night
8%424323347%54%
54439
Cloud CoverDay
8%5%2442445%7%51%
55066
Night
8%42432335%7%54%
54439
TransparencyDay
31%413%27%18%4
54766
Night
29%312%27%21%5%
54244
SeeingDay
11%6%26%32%19%4
8286
Night
10%6%31%36%13%
18344

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%6%24422347%56%
1881
16th to endDay
6%5%2442335%7%54%
2016
February1st to 15thDay
7%7%25%434436%48%
1935
16th to endDay
7%6%25%3245%47%50%
1840
March1st to 15thDay
9%5%2442345%6%50%
2242
16th to endDay
15%6%2441335%7%46%
2464
April1st to 15thDay
11%6%343235%47%47%
2379
16th to endDay
14%6%25%5%23446%43%
2694
May1st to 15thDay
11%5%3443445%7%46%
2721
16th to endDay
10%6%25%4245%6%6%44%
2846
June1st to 15thDay
6%32432345%8%54%
2730
16th to endDay
42123345%5%9%57%
2730
July1st to 15thDay
5%324435%5%6%10%48%
2730
16th to endDay
5%3134246%6%10%52%
2677
August1st to 15thDay
7%4144345%6%10%48%
2486
16th to endDay
6%3244245%6%8%54%
2627
September1st to 15thDay
9%5%2442445%5%49%
2145
16th to endDay
8%314423445%55%
2145
October1st to 15thDay
16%412212335%53%
2054
16th to endDay
6%5%13312245%62%
2077
November1st to 15thDay
7%414323435%59%
1853
16th to endDay
8%41331222465%
1890
December1st to 15thDay
10%6%24413347%51%
1890
16th to endDay
10%8%45%414345%47%
2016
January1st to 15thNight
7%5%24323345%55%
2717
16th to endNight
5%42331334462%
2912
February1st to 15thNight
10%7%25%423446%48%
2588
16th to endNight
8%6%2432335%7%51%
2206
March1st to 15thNight
7%6%2432445%7%52%
2377
16th to endNight
13%6%24324446%47%
2464
April1st to 15thNight
10%5%2442345%8%49%
2225
16th to endNight
14%6%24323346%48%
1871
May1st to 15thNight
13%423423448%47%
1889
16th to endNight
10%3234145%7%10%46%
1971
June1st to 15thNight
6%21331446%10%55%
1890
16th to endNight
311232446%9%60%
1890
July1st to 15thNight
411342446%9%57%
1890
16th to endNight
5%31332347%11%53%
1855
August1st to 15thNight
4214425%45%10%52%
1727
16th to endNight
5%32442345%7%57%
1924
September1st to 15thNight
8%425%5%24447%51%
2143
16th to endNight
6%31332445%6%59%
2145
October1st to 15thNight
14%414323245%53%
2222
16th to endNight
7%3321223467%
2496
November1st to 15thNight
6%323212246%62%
2665
16th to endNight
9%412312336%61%
2730
December1st to 15thNight
9%424324346%53%
2730
16th to endNight
10%6%34423348%48%
2912

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%24322347%56%
1881
16th to endDay
7%5%24423347%54%
2016
February1st to 15thDay
7%7%35%5%25%436%48%
1935
16th to endDay
7%6%25%3245%5%7%50%
1840
March1st to 15thDay
9%5%2442445%6%50%
2242
16th to endDay
15%6%1441335%7%46%
2462
April1st to 15thDay
11%6%343235%48%47%
2379
16th to endDay
15%6%25%5%23446%42%
2694
May1st to 15thDay
11%5%3443445%7%46%
2721
16th to endDay
10%6%25%5%245%5%7%44%
2846
June1st to 15thDay
6%42432346%8%54%
2730
16th to endDay
42124245%5%9%57%
2730
July1st to 15thDay
5%3245%35%5%5%10%48%
2730
16th to endDay
5%2134245%7%10%52%
2677
August1st to 15thDay
6%4144345%6%10%48%
2486
16th to endDay
6%3143245%5%8%54%
2627
September1st to 15thDay
9%5%24425%45%6%49%
2145
16th to endDay
8%324424345%55%
2145
October1st to 15thDay
15%412312345%54%
2054
16th to endDay
6%5%13312235%62%
2077
November1st to 15thDay
7%413423435%59%
1853
16th to endDay
8%41331222464%
1890
December1st to 15thDay
10%6%2441335%6%51%
1890
16th to endDay
10%8%45%414336%46%
2016
January1st to 15thNight
7%5%24323345%55%
2717
16th to endNight
5%42331334462%
2912
February1st to 15thNight
10%7%25%423446%48%
2588
16th to endNight
8%5%2432335%6%51%
2206
March1st to 15thNight
7%6%2432445%7%52%
2377
16th to endNight
14%6%24314446%47%
2464
April1st to 15thNight
10%41442345%8%48%
2225
16th to endNight
14%6%24323346%48%
1871
May1st to 15thNight
13%42442335%8%46%
1889
16th to endNight
9%32441447%11%46%
1971
June1st to 15thNight
5%21331446%10%55%
1890
16th to endNight
31232446%9%61%
1890
July1st to 15thNight
411332446%9%57%
1890
16th to endNight
5%31332347%10%54%
1855
August1st to 15thNight
422443445%10%52%
1727
16th to endNight
5%31442345%7%57%
1924
September1st to 15thNight
8%425%5%24447%51%
2143
16th to endNight
6%31332345%6%59%
2145
October1st to 15thNight
14%424323245%53%
2222
16th to endNight
7%3321223467%
2496
November1st to 15thNight
6%323212346%62%
2665
16th to endNight
9%412222336%61%
2730
December1st to 15thNight
9%42432435%6%53%
2730
16th to endNight
10%6%34423347%48%
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
28%214%32%18%2
1882
16th to endDay
29%215%30%17%3
2016
February1st to 15thDay
37%414%28%11%3
1936
16th to endDay
32%413%27%18%4
1840
March1st to 15thDay
33%411%24%21%4
2242
16th to endDay
38%413%26%14%2
2464
April1st to 15thDay
35%413%28%14%2
2379
16th to endDay
41%412%27%12%2
2694
May1st to 15thDay
35%6%13%23%18%1
2721
16th to endDay
37%5%15%27%12%2
2850
June1st to 15thDay
27%416%27%18%5%
2730
16th to endDay
22%5%13%29%22%6%
2730
July1st to 15thDay
28%6%15%29%16%3
2591
16th to endDay
24%416%31%20%3
2522
August1st to 15thDay
29%5%17%26%14%4
2472
16th to endDay
26%5%13%29%18%6%
2627
September1st to 15thDay
34%5%11%24%16%7%
2145
16th to endDay
29%410%30%21%5%
2145
October1st to 15thDay
32%210%24%23%5%
2054
16th to endDay
25%29%29%25%6%
2077
November1st to 15thDay
28%210%25%25%7%
1853
16th to endDay
24%210%31%25%4
1890
December1st to 15thDay
33%313%29%18%1
1890
16th to endDay
39%311%25%16%3
2016
January1st to 15thNight
31%211%28%23%3
2717
16th to endNight
25%212%29%24%4
2912
February1st to 15thNight
37%314%25%15%3
2598
16th to endNight
33%211%25%18%8%
2206
March1st to 15thNight
31%310%25%21%7%
2377
16th to endNight
38%312%26%16%3
2464
April1st to 15thNight
32%412%25%21%2
2225
16th to endNight
36%413%21%20%3
1871
May1st to 15thNight
36%414%25%16%2
1890
16th to endNight
30%6%20%27%13%1
1973
June1st to 15thNight
22%5%18%30%19%3
1890
16th to endNight
18%416%32%23%5%
1890
July1st to 15thNight
20%5%15%30%22%4
1800
16th to endNight
23%5%17%29%20%3
1747
August1st to 15thNight
25%5%16%31%15%5%
1717
16th to endNight
25%5%13%27%21%7%
1924
September1st to 15thNight
32%412%24%17%8%
2143
16th to endNight
24%310%25%29%6%
2145
October1st to 15thNight
33%39%22%23%7%
2222
16th to endNight
21%28%27%31%8%
2496
November1st to 15thNight
24%29%26%28%8%
2665
16th to endNight
25%29%30%25%6%
2730
December1st to 15thNight
31%313%27%20%3
2730
16th to endNight
35%312%27%16%5%
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
13%8%35%31%11%1
180
16th to endDay
12%10%39%31%5%
192
February1st to 15thDay
13%12%43%24%41
180
16th to endDay
10%8%52%20%5%1
159
March1st to 15thDay
15%12%39%26%6%
180
16th to endDay
18%8%38%27%6%1
192
April1st to 15thDay
13%13%38%26%7%
258
16th to endDay
17%10%37%22%9%1
586
May1st to 15thDay
13%8%31%28%13%3
618
16th to endDay
14%7%30%27%15%4
677
June1st to 15thDay
8%325%36%21%4
645
16th to endDay
4326%42%20%2
645
July1st to 15thDay
6%210%39%32%8%
625
16th to endDay
5%11%39%34%8%
597
August1st to 15thDay
9%29%38%34%5%
549
16th to endDay
6%314%38%29%6%
539
September1st to 15thDay
8%114%37%30%7%
180
16th to endDay
14%222%27%21%11%
180
October1st to 15thDay
17%8%27%28%11%6%
180
16th to endDay
8%8%29%32%16%4
192
November1st to 15thDay
17%6%28%26%15%4
180
16th to endDay
16%10%32%27%11%1
180
December1st to 15thDay
7%12%43%25%10%1
180
16th to endDay
14%13%42%23%5%
192
January1st to 15thNight
9%9%36%36%7%
1050
16th to endNight
7%8%41%35%7%
1120
February1st to 15thNight
13%8%39%33%4
950
16th to endNight
11%10%40%32%4
736
March1st to 15thNight
10%11%38%34%6%
697
16th to endNight
16%8%39%28%5%
672
April1st to 15thNight
12%10%38%30%7%
629
16th to endNight
18%9%34%30%7%
624
May1st to 15thNight
15%7%32%32%11%
630
16th to endNight
11%5%28%35%16%2
659
June1st to 15thNight
6%329%40%18%
630
16th to endNight
3134%43%16%
630
July1st to 15thNight
412%52%27%2
600
16th to endNight
6%112%46%30%1
615
August1st to 15thNight
5%19%53%28%1
575
16th to endNight
7%116%38%34%1
621
September1st to 15thNight
10%321%40%21%2
585
16th to endNight
7%324%40%21%1
582
October1st to 15thNight
17%5%28%30%16%1
662
16th to endNight
9%5%34%38%12%
832
November1st to 15thNight
8%6%34%35%13%
1025
16th to endNight
11%9%31%36%9%
1050
December1st to 15thNight
12%8%36%35%7%
1050
16th to endNight
13%8%35%35%6%
1120
Page generated at 2019-07-17 07:53:05. Version ac04

Copyright 2019 A. Danko


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