Crane Point Nature Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Crane Point Nature Center clear sky chart from 2005-11-06 to 2024-03-28.

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
71%
25209
18%
80232
18%
25141
72%
25141
28%
50488

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 10thNight
68%
743
20%
4034
25%
737
70%
737
20%
2229
January11th to 20thNight
56%
746
13%
4090
20%
740
60%
740
13%
2815
January21st to endNight
58%
824
17%
4156
22%
814
64%
814
17%
2525
February1st to 10thNight
66%
760
27%
2280
25%
760
69%
760
33%
1355
February11th to 20thNight
67%
739
28%
2138
23%
739
72%
739
41%
1192
February21st to endNight
76%
628
33%
1727
29%
628
78%
628
49%
928
March1st to 10thNight
69%
760
27%
2090
22%
760
73%
760
42%
1214
March11th to 20thNight
76%
760
28%
2090
23%
760
78%
760
45%
1166
March21st to endNight
72%
821
29%
2256
25%
821
75%
821
44%
1285
April1st to 10thNight
81%
720
24%
1980
22%
720
83%
720
47%
1076
April11th to 20thNight
74%
711
21%
1950
18%
711
75%
711
40%
1155
April21st to endNight
77%
720
29%
1800
21%
720
77%
720
43%
1080
May1st to 10thNight
83%
720
28%
1800
20%
720
83%
720
57%
971
May11th to 20thNight
67%
684
14%
1745
10%
684
68%
684
31%
1187
May21st to endNight
70%
582
18%
1745
16%
582
70%
582
27%
1115
June1st to 10thNight
54%
540
9%
1620
9%
540
54%
540
15%
1224
June11th to 20thNight
75%
540
9%
1620
9%
540
75%
540
23%
1099
June21st to endNight
77%
540
9%
1620
9%
540
77%
540
24%
1082
July1st to 10thNight
81%
525
9%
1575
8%
525
81%
525
31%
946
July11th to 20thNight
78%
522
10%
1566
10%
522
78%
522
28%
986
July21st to endNight
82%
591
11%
1672
12%
558
83%
558
32%
989
August1st to 10thNight
81%
537
10%
1600
9%
534
80%
534
29%
1007
August11th to 20thNight
81%
707
8%
1919
7%
707
81%
707
33%
1215
August21st to endNight
72%
792
7%
2178
6%
792
72%
792
22%
1578
September1st to 10thNight
78%
720
7%
1980
7%
720
78%
720
26%
1390
September11th to 20thNight
70%
720
7%
1980
6%
720
70%
720
20%
1453
September21st to endNight
65%
720
9%
1980
9%
720
65%
720
18%
1487
October1st to 10thNight
69%
720
14%
1998
14%
720
69%
720
22%
1443
October11th to 20thNight
69%
720
13%
2160
15%
720
70%
720
23%
1459
October21st to endNight
64%
792
19%
2376
20%
792
65%
792
23%
1612
November1st to 10thNight
62%
740
21%
2221
19%
740
66%
740
30%
1374
November11th to 20thNight
67%
760
24%
2280
26%
760
68%
760
29%
1443
November21st to endNight
68%
760
25%
2280
25%
760
70%
760
30%
1407
December1st to 10thNight
70%
760
23%
2308
22%
760
73%
760
30%
1412
December11th to 20thNight
66%
759
22%
2922
22%
758
68%
758
26%
1645
December21st to endNight
66%
826
13%
4496
24%
817
69%
817
16%
2944

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%425%5%46%7%8%12%41%
79188
Night
6%5%25%6%46%6%8%11%41%
80793
TransparencyDay
32%11%21%22%11%2
78911
Night
35%10%18%22%13%2
80589
SeeingDay
6%27%22%37%25%
15074
Night
7%29%26%37%19%
25269

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 10thDay
9%5%25%6%35%5%7%13%40%
2836
11th to 20thDay
10%7%37%7%45%7%7%9%33%
2840
21st to endDay
5%6%36%6%47%6%7%8%41%
3391
February1st to 10thDay
6%424435%7%7%10%50%
1900
11th to 20thDay
5%42342446%10%57%
1925
21st to endDay
421232346%10%63%
1727
March1st to 10thDay
23133345%7%12%56%
2090
11th to 20thDay
4312335%5%7%10%57%
2090
21st to endDay
431342345%10%60%
2255
April1st to 10thDay
22122345%6%13%59%
1980
11th to 20thDay
33233245%7%12%58%
1956
21st to endDay
43133245%7%11%57%
2160
May1st to 10thDay
321332346%10%65%
2160
11th to 20thDay
9%5%35%5%46%6%7%12%39%
2160
21st to endDay
8%5%35%6%46%6%7%12%38%
2531
June1st to 10thDay
11%7%38%7%46%8%9%11%25%
2340
11th to 20thDay
6%426%7%5%7%8%9%15%30%
2340
21st to endDay
5%435%7%5%6%7%9%15%32%
2340
July1st to 10thDay
4425%5%48%8%10%15%36%
2340
11th to 20thDay
4325%5%48%9%12%17%31%
2340
21st to endDay
33246%5%7%8%11%17%33%
2547
August1st to 10thDay
3326%8%5%8%9%12%15%29%
2310
11th to 20thDay
3325%7%5%7%10%10%16%33%
1972
21st to endDay
6%435%8%5%8%9%11%14%28%
2178
September1st to 10thDay
6%426%7%5%8%11%11%15%26%
1980
11th to 20thDay
5%5%35%7%5%7%9%10%14%30%
1980
21st to endDay
8%6%37%8%5%8%8%9%12%27%
1980
October1st to 10thDay
7%5%26%7%5%7%7%9%14%30%
1959
11th to 20thDay
7%5%26%7%47%8%8%12%34%
1800
21st to endDay
8%6%35%5%36%6%7%10%41%
1980
November1st to 10thDay
7%425%5%245%8%8%49%
1857
11th to 20thDay
7%5%345%46%7%7%9%43%
1900
21st to endDay
5%4245%35%5%7%10%49%
1900
December1st to 10thDay
7%314435%6%7%12%47%
1867
11th to 20thDay
7%5%245%36%6%7%11%46%
2153
21st to endDay
11%5%36%5%35%6%7%10%37%
3124
January1st to 10thNight
7%5%25%6%45%7%7%11%41%
4109
11th to 20thNight
12%8%47%8%46%6%7%8%29%
4120
21st to endNight
7%5%27%7%5%6%6%6%9%40%
4248
February1st to 10thNight
6%425%5%46%6%6%9%48%
2280
11th to 20thNight
6%324425%5%6%8%55%
2138
21st to endNight
33233335%5%8%61%
1727
March1st to 10thNight
3315%5%35%6%6%10%53%
2090
11th to 20thNight
42244346%6%9%57%
2090
21st to endNight
43245%25%46%8%57%
2256
April1st to 10thNight
3213435%5%6%11%56%
1980
11th to 20thNight
5%424425%5%6%11%52%
1950
21st to endNight
5%424425%5%6%10%53%
1800
May1st to 10thNight
321332345%11%64%
1800
11th to 20thNight
8%6%37%5%45%5%8%11%39%
1745
21st to endNight
9%425%6%37%6%8%10%39%
1744
June1st to 10thNight
12%9%49%9%5%6%6%8%10%23%
1620
11th to 20thNight
5%435%7%5%6%7%9%15%34%
1620
21st to endNight
4335%7%5%8%8%9%15%33%
1620
July1st to 10thNight
3325%5%46%7%9%15%42%
1620
11th to 20thNight
3335%6%48%7%9%15%38%
1620
21st to endNight
2325%6%47%8%10%13%41%
1771
August1st to 10thNight
3425%6%47%7%11%17%35%
1611
11th to 20thNight
33247%47%7%10%15%38%
1919
21st to endNight
6%6%26%7%5%7%8%9%15%30%
2178
September1st to 10thNight
5%325%7%48%10%10%14%33%
1980
11th to 20thNight
46%38%8%5%7%8%10%12%29%
1980
21st to endNight
8%7%47%7%6%8%7%9%11%26%
1980
October1st to 10thNight
7%6%26%8%5%8%8%8%14%29%
1998
11th to 20thNight
8%5%27%6%46%8%10%13%31%
2160
21st to endNight
10%7%36%6%46%6%8%9%35%
2376
November1st to 10thNight
9%425%435%6%6%11%44%
2221
11th to 20thNight
8%5%25%5%46%5%6%11%42%
2280
21st to endNight
7%425%5%36%6%8%9%45%
2280
December1st to 10thNight
6%435%5%46%6%7%9%46%
2308
11th to 20thNight
7%5%25%5%35%5%7%11%46%
3042
21st to endNight
10%6%37%7%46%6%7%10%33%
4532

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 10thDay
35%9%17%27%10%3
2837
11th to 20thDay
44%10%16%21%7%2
2840
21st to endDay
38%8%11%22%17%4
3391
February1st to 10thDay
29%7%12%31%18%3
1900
11th to 20thDay
24%5%13%29%23%6%
1935
21st to endDay
17%6%11%30%30%6%
1727
March1st to 10thDay
22%6%14%33%22%3
2090
11th to 20thDay
21%7%14%36%18%4
2090
21st to endDay
21%5%16%32%22%4
2255
April1st to 10thDay
18%7%17%43%13%2
1980
11th to 20thDay
21%7%20%33%18%2
1956
21st to endDay
19%7%17%34%20%3
2160
May1st to 10thDay
16%5%20%33%21%4
2160
11th to 20thDay
36%9%21%26%8%
2164
21st to endDay
36%10%18%24%11%1
2531
June1st to 10thDay
48%11%22%15%3
2340
11th to 20thDay
39%15%31%15%1
2340
21st to endDay
35%16%37%12%1
2340
July1st to 10thDay
32%17%38%13%1
2275
11th to 20thDay
32%15%38%15%1
2271
21st to endDay
29%17%37%15%2
2405
August1st to 10thDay
32%18%31%17%2
2297
11th to 20thDay
32%15%39%14%1
1972
21st to endDay
38%18%30%13%1
2178
September1st to 10thDay
38%18%29%14%1
1980
11th to 20thDay
39%17%28%14%2
1980
21st to endDay
43%15%24%13%4
1980
October1st to 10thDay
40%12%21%18%6%2
1959
11th to 20thDay
39%11%18%20%10%2
1800
21st to endDay
37%8%14%22%15%4
1980
November1st to 10thDay
31%8%13%24%20%4
1857
11th to 20thDay
37%8%11%23%18%4
1900
21st to endDay
31%8%13%22%22%3
1900
December1st to 10thDay
30%9%14%27%18%1
1867
11th to 20thDay
31%9%11%23%20%6%
2150
21st to endDay
41%10%15%17%15%2
3124
January1st to 10thNight
35%8%14%27%14%2
4109
11th to 20thNight
50%9%14%17%8%2
4120
21st to endNight
41%7%9%22%18%3
4248
February1st to 10thNight
32%7%12%28%18%3
2280
11th to 20thNight
27%5%12%25%23%8%
2139
21st to endNight
23%412%23%29%9%
1727
March1st to 10thNight
26%7%12%29%22%3
2090
11th to 20thNight
24%6%14%32%22%2
2090
21st to endNight
25%6%12%29%23%5%
2256
April1st to 10thNight
22%6%17%38%15%2
1980
11th to 20thNight
28%7%16%29%18%3
1950
21st to endNight
27%7%12%32%20%3
1800
May1st to 10thNight
16%6%17%35%22%4
1800
11th to 20thNight
37%10%17%24%12%
1746
21st to endNight
37%9%16%24%13%1
1745
June1st to 10thNight
54%10%19%13%3
1620
11th to 20thNight
36%15%31%15%2
1620
21st to endNight
35%15%34%15%1
1620
July1st to 10thNight
27%14%41%17%1
1575
11th to 20thNight
31%14%36%18%1
1566
21st to endNight
26%13%39%19%3
1672
August1st to 10thNight
31%14%34%20%2
1600
11th to 20thNight
29%13%38%19%1
1919
21st to endNight
40%16%30%13%1
2178
September1st to 10thNight
35%17%33%14%1
1980
11th to 20thNight
44%15%28%12%2
1980
21st to endNight
48%13%22%13%4
1980
October1st to 10thNight
44%12%19%16%8%1
1998
11th to 20thNight
40%12%20%19%8%2
2160
21st to endNight
44%8%10%19%15%3
2376
November1st to 10thNight
35%8%14%24%16%3
2221
11th to 20thNight
37%8%12%23%17%3
2280
21st to endNight
34%9%13%22%20%2
2280
December1st to 10thNight
34%8%15%25%17%1
2308
11th to 20thNight
34%6%13%26%15%6%
3044
21st to endNight
45%9%14%17%14%1
4532

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 10thDay
9%416%34%34%3
270
11th to 20thDay
10%416%42%24%4
270
21st to endDay
9%420%41%24%2
297
February1st to 10thDay
3415%39%36%3
270
11th to 20thDay
5%311%33%42%7%
347
21st to endDay
4113%32%44%7%
382
March1st to 10thDay
5%214%43%33%3
460
11th to 20thDay
6%114%37%38%4
460
21st to endDay
4312%34%43%4
490
April1st to 10thDay
29%41%45%3
420
11th to 20thDay
319%41%40%5%
412
21st to endDay
6%1439%47%3
420
May1st to 10thDay
5%430%49%12%
423
11th to 20thDay
10%15%27%45%13%
447
21st to endDay
10%1414%48%22%
485
June1st to 10thDay
11%2416%35%31%
450
11th to 20thDay
6%2210%35%46%
450
21st to endDay
415%28%62%
450
July1st to 10thDay
31330%62%
445
11th to 20thDay
32430%61%
444
21st to endDay
5%11430%59%
488
August1st to 10thDay
41336%55%
446
11th to 20thDay
215%34%57%
439
21st to endDay
6%148%36%45%
495
September1st to 10thDay
7%126%28%56%
450
11th to 20thDay
5%126%26%60%
450
21st to endDay
8%249%31%46%
450
October1st to 10thDay
6%1419%52%19%
450
11th to 20thDay
10%26%21%40%21%
450
21st to endDay
9%310%23%41%14%
495
November1st to 10thDay
7%312%27%40%11%
455
11th to 20thDay
7%314%29%37%10%
460
21st to endDay
6%214%31%38%9%
460
December1st to 10thDay
10%210%28%41%9%
427
11th to 20thDay
6%313%26%40%12%
270
21st to endDay
9%413%27%40%8%
297
January1st to 10thNight
7%314%33%37%6%
760
11th to 20thNight
10%319%34%31%3
760
21st to endNight
7%6%21%32%32%2
836
February1st to 10thNight
7%416%36%35%2
760
11th to 20thNight
6%218%36%33%5%
743
21st to endNight
4212%33%43%6%
628
March1st to 10thNight
3217%42%32%3
760
11th to 20thNight
3113%39%40%4
760
21st to endNight
4215%38%36%3
821
April1st to 10thNight
219%43%42%3
720
11th to 20thNight
6%312%40%37%3
711
21st to endNight
5%19%42%39%3
720
May1st to 10thNight
417%32%46%11%
720
11th to 20thNight
9%27%28%45%9%
684
21st to endNight
9%17%18%49%16%
584
June1st to 10thNight
14%37%17%41%18%
540
11th to 20thNight
5%1210%42%39%
540
21st to endNight
4119%32%53%
540
July1st to 10thNight
225%32%58%
525
11th to 20thNight
3117%36%52%
522
21st to endNight
3125%31%58%
591
August1st to 10thNight
316%40%50%
537
11th to 20thNight
4116%34%55%
707
21st to endNight
8%1310%35%44%
792
September1st to 10thNight
6%127%34%51%
720
11th to 20thNight
8%39%28%52%
720
21st to endNight
10%1410%34%39%
720
October1st to 10thNight
8%16%19%47%19%
720
11th to 20thNight
9%16%20%43%21%
720
21st to endNight
13%29%29%34%13%
792
November1st to 10thNight
11%314%27%36%8%
740
11th to 20thNight
8%211%30%40%9%
760
21st to endNight
7%214%35%36%7%
760
December1st to 10thNight
8%311%32%39%8%
760
11th to 20thNight
8%413%30%39%6%
760
21st to endNight
7%314%32%35%8%
836
Page generated at 2024-03-24 23:36:59. Version ac07

Copyright © 2024 Attilla Danko.


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