Whitin Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Whitin Observatory clear sky chart from 2005-11-06 to 2024-03-18.

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
26%
23198
18%
80688
8%
23107
38%
23107
18%
51920

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
16%
752
23%
4327
6%
737
34%
737
12%
2336
January11th to 20thNight
14%
759
23%
4349
3%
740
31%
740
9%
2584
January21st to endNight
16%
830
12%
4863
6%
814
34%
814
8%
3405
February1st to 10thNight
18%
760
18%
2398
6%
760
34%
760
17%
1594
February11th to 20thNight
14%
743
20%
2220
5%
740
32%
740
18%
1485
February21st to endNight
18%
628
23%
1884
8%
628
37%
628
18%
1245
March1st to 10thNight
19%
760
21%
2280
7%
760
37%
760
19%
1526
March11th to 20thNight
17%
752
18%
2152
5%
752
31%
752
18%
1481
March21st to endNight
19%
792
22%
2062
6%
792
32%
792
20%
1442
April1st to 10thNight
20%
720
19%
1800
4%
720
30%
720
20%
1268
April11th to 20thNight
21%
698
17%
1762
4%
698
29%
698
22%
1230
April21st to endNight
19%
540
19%
1620
5%
540
30%
540
17%
1096
May1st to 10thNight
19%
540
13%
1620
6%
540
25%
540
15%
1168
May11th to 20thNight
20%
518
15%
1580
6%
518
29%
518
18%
1063
May21st to endNight
30%
389
12%
1551
10%
388
39%
388
17%
978
June1st to 10thNight
29%
360
13%
1440
8%
360
42%
360
16%
943
June11th to 20thNight
30%
360
13%
1440
11%
360
40%
360
18%
930
June21st to endNight
36%
360
12%
1440
9%
360
47%
360
21%
867
July1st to 10thNight
41%
350
13%
1400
12%
350
50%
350
22%
840
July11th to 20thNight
41%
348
13%
1392
12%
348
48%
348
20%
854
July21st to endNight
42%
394
18%
1486
16%
372
51%
372
23%
883
August1st to 10thNight
42%
495
16%
1559
10%
493
46%
493
29%
945
August11th to 20thNight
44%
557
17%
1621
10%
557
48%
557
24%
1079
August21st to endNight
50%
792
21%
1980
10%
792
54%
792
35%
1266
September1st to 10thNight
39%
720
20%
1804
8%
720
45%
720
31%
1206
September11th to 20thNight
42%
720
25%
1980
13%
720
51%
720
33%
1204
September21st to endNight
39%
720
23%
1980
14%
720
48%
720
29%
1294
October1st to 10thNight
34%
720
18%
1980
10%
720
41%
720
23%
1330
October11th to 20thNight
33%
720
22%
2194
10%
720
47%
720
26%
1359
October21st to endNight
23%
792
16%
2574
6%
792
36%
792
18%
1729
November1st to 10thNight
30%
740
22%
2407
11%
740
44%
740
23%
1463
November11th to 20thNight
22%
760
24%
2470
9%
760
41%
760
20%
1534
November21st to endNight
21%
760
22%
2470
6%
760
40%
760
19%
1521
December1st to 10thNight
18%
760
19%
2617
6%
760
33%
760
16%
1717
December11th to 20thNight
20%
760
18%
3193
4%
759
35%
759
13%
1958
December21st to endNight
17%
829
15%
4793
5%
817
35%
817
10%
3097

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
17%6%35%5%3445%7%40%
78524
Night
17%7%35%5%3445%6%41%
81260
TransparencyDay
43%6%11%22%15%3
78229
Night
44%6%12%22%15%2
81089
SeeingDay
23%16%33%19%7%2
14159
Night
22%14%33%24%6%1
23220

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 10thDay
14%8%26%5%34445%46%
2517
11th to 20thDay
17%7%46%4345%5%5%41%
2520
21st to endDay
22%11%35%5%3445%6%33%
2772
February1st to 10thDay
20%6%45%5%35%5%5%6%37%
1779
11th to 20thDay
13%8%35%6%35%46%6%40%
1848
21st to endDay
19%9%35%445%35%5%38%
1570
March1st to 10thDay
18%8%35%435%5%5%7%38%
1897
11th to 20thDay
16%6%36%5%35%45%7%39%
1971
21st to endDay
19%7%36%434446%40%
2293
April1st to 10thDay
20%7%36%5%34446%38%
2160
11th to 20thDay
18%6%25%5%345%5%7%39%
2146
21st to endDay
22%5%26%5%35%46%6%35%
2340
May1st to 10thDay
25%9%36%5%34446%32%
2340
11th to 20thDay
18%7%25%5%44446%41%
2328
21st to endDay
15%5%35%6%3445%8%43%
2725
June1st to 10thDay
20%6%26%5%35%5%6%9%34%
2520
11th to 20thDay
17%6%35%5%445%6%7%37%
2520
21st to endDay
16%5%26%6%45%6%6%8%35%
2520
July1st to 10thDay
14%5%25%5%36%6%5%8%41%
2520
11th to 20thDay
12%5%27%5%35%5%6%9%40%
2520
21st to endDay
12%435%6%45%6%6%9%40%
2744
August1st to 10thDay
10%5%35%7%46%6%7%8%39%
2350
11th to 20thDay
13%6%25%5%46%6%6%7%39%
2276
21st to endDay
13%5%245%35%5%6%8%44%
2376
September1st to 10thDay
15%425%5%35%5%5%6%46%
2155
11th to 20thDay
15%6%24333346%51%
1980
21st to endDay
18%5%2442435%6%46%
1980
October1st to 10thDay
25%5%245%24336%41%
1980
11th to 20thDay
15%6%245%33446%47%
1765
21st to endDay
21%7%345%34446%40%
1782
November1st to 10thDay
17%6%2442434450%
1671
11th to 20thDay
19%6%2433335%5%46%
1710
21st to endDay
18%5%3442445%6%43%
1710
December1st to 10thDay
17%8%36%5%35%445%40%
1561
11th to 20thDay
22%6%33334435%45%
1906
21st to endDay
22%10%36%5%3445%5%34%
2772
January1st to 10thNight
18%8%24323335%48%
4429
11th to 20thNight
15%9%37%6%34346%40%
4440
21st to endNight
21%14%47%6%34445%30%
4884
February1st to 10thNight
17%9%35%5%3445%5%39%
2398
11th to 20thNight
15%9%36%5%345%47%39%
2218
21st to endNight
19%9%25%434345%42%
1884
March1st to 10thNight
18%8%35%5%3445%6%41%
2270
11th to 20thNight
16%9%36%5%35%5%5%5%39%
2152
21st to endNight
17%9%35%5%34345%41%
2062
April1st to 10thNight
19%7%26%5%3445%7%38%
1800
11th to 20thNight
19%6%26%434446%40%
1762
21st to endNight
22%8%35%5%34345%39%
1620
May1st to 10thNight
24%8%36%5%3445%6%32%
1620
11th to 20thNight
19%5%35%445%5%6%8%37%
1579
21st to endNight
17%7%36%5%335%49%39%
1550
June1st to 10thNight
17%8%35%5%35%45%7%37%
1440
11th to 20thNight
19%5%46%5%35%45%8%37%
1440
21st to endNight
15%5%244346%5%10%42%
1440
July1st to 10thNight
13%5%35%6%345%7%9%40%
1440
11th to 20thNight
12%7%38%5%35%46%10%36%
1440
21st to endNight
13%5%35%435%5%6%9%41%
1574
August1st to 10thNight
9%5%25%6%345%8%8%46%
1569
11th to 20thNight
11%5%25%6%47%5%7%9%38%
1621
21st to endNight
14%5%1443445%8%48%
1980
September1st to 10thNight
14%5%35%5%345%5%6%46%
1804
11th to 20thNight
14%5%23324446%53%
1980
21st to endNight
17%6%245%235%5%5%45%
1980
October1st to 10thNight
22%6%25%424445%43%
1980
11th to 20thNight
16%6%25%43445%6%46%
2194
21st to endNight
22%7%35%5%34346%38%
2574
November1st to 10thNight
15%6%25%434445%48%
2407
11th to 20thNight
18%6%35%324445%46%
2470
21st to endNight
17%5%35%434446%45%
2470
December1st to 10thNight
19%8%35%5%25%446%39%
2617
11th to 20thNight
20%7%25%42445%5%42%
3288
21st to endNight
21%10%36%5%24446%35%
4884

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
40%5%9%32%13%2
2518
11th to 20thDay
45%6%9%25%13%2
2520
21st to endDay
51%5%11%22%9%1
2772
February1st to 10thDay
47%5%14%18%14%3
1779
11th to 20thDay
43%6%11%22%15%3
1857
21st to endDay
48%5%10%20%14%3
1570
March1st to 10thDay
45%5%12%21%13%4
1900
11th to 20thDay
43%6%11%21%15%4
1971
21st to endDay
46%5%8%18%17%6%
2293
April1st to 10thDay
47%5%9%19%16%4
2160
11th to 20thDay
43%6%11%20%17%3
2146
21st to endDay
47%6%9%18%16%4
2340
May1st to 10thDay
53%49%18%13%2
2340
11th to 20thDay
43%6%11%19%18%4
2332
21st to endDay
39%7%13%24%14%2
2725
June1st to 10thDay
47%7%13%23%10%1
2520
11th to 20thDay
44%7%12%19%16%2
2520
21st to endDay
45%8%13%21%13%1
2520
July1st to 10thDay
40%8%11%24%14%3
2450
11th to 20thDay
40%8%14%25%12%2
2445
21st to endDay
39%8%14%22%13%4
2591
August1st to 10thDay
39%9%14%24%13%1
2336
11th to 20thDay
41%9%13%23%13%1
2276
21st to endDay
37%7%10%25%19%2
2376
September1st to 10thDay
37%7%11%24%19%2
2155
11th to 20thDay
35%48%27%22%3
1980
21st to endDay
40%49%22%23%2
1980
October1st to 10thDay
46%5%9%22%14%4
1980
11th to 20thDay
37%6%11%29%16%2
1765
21st to endDay
45%5%13%19%15%4
1782
November1st to 10thDay
39%313%25%17%3
1671
11th to 20thDay
41%49%24%20%2
1710
21st to endDay
41%5%14%25%12%2
1710
December1st to 10thDay
47%5%14%16%18%1
1561
11th to 20thDay
44%313%18%16%5%
1906
21st to endDay
51%6%11%20%11%1
2772
January1st to 10thNight
40%412%29%13%3
4429
11th to 20thNight
46%412%22%12%3
4440
21st to endNight
57%5%10%16%11%2
4884
February1st to 10thNight
46%5%13%21%13%2
2398
11th to 20thNight
45%5%10%20%16%4
2220
21st to endNight
45%48%24%15%4
1884
March1st to 10thNight
45%5%9%22%16%4
2280
11th to 20thNight
46%6%11%16%17%4
2153
21st to endNight
47%47%17%19%6%
2062
April1st to 10thNight
46%5%11%19%16%3
1800
11th to 20thNight
45%5%9%21%17%3
1762
21st to endNight
47%6%10%18%15%4
1620
May1st to 10thNight
53%5%10%16%13%3
1620
11th to 20thNight
44%7%13%18%13%4
1580
21st to endNight
45%6%15%20%13%1
1551
June1st to 10thNight
47%7%13%21%11%1
1440
11th to 20thNight
45%7%12%21%13%1
1440
21st to endNight
38%9%14%24%13%1
1440
July1st to 10thNight
38%8%15%23%16%1
1400
11th to 20thNight
41%8%15%27%9%1
1392
21st to endNight
38%8%14%27%12%2
1486
August1st to 10thNight
33%9%18%24%14%2
1559
11th to 20thNight
40%9%16%21%13%
1621
21st to endNight
35%6%13%26%20%1
1980
September1st to 10thNight
39%6%12%24%18%1
1804
11th to 20thNight
34%5%10%23%26%2
1980
21st to endNight
39%6%9%22%21%3
1980
October1st to 10thNight
45%5%12%22%13%4
1980
11th to 20thNight
38%6%13%28%15%1
2194
21st to endNight
48%413%19%15%1
2574
November1st to 10thNight
38%5%11%23%19%4
2407
11th to 20thNight
41%410%23%19%3
2470
21st to endNight
40%414%26%14%2
2470
December1st to 10thNight
46%6%12%21%14%1
2617
11th to 20thNight
44%5%15%17%18%1
3288
21st to endNight
49%6%9%25%10%1
4884

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
27%22%31%16%4
180
11th to 20thDay
29%22%35%11%3
180
21st to endDay
25%23%34%13%5%
198
February1st to 10thDay
30%18%33%16%2
377
11th to 20thDay
27%23%37%11%2
456
21st to endDay
29%18%34%16%31
382
March1st to 10thDay
30%17%33%16%3
460
11th to 20thDay
29%21%32%13%41
449
21st to endDay
28%20%33%8%8%2
462
April1st to 10thDay
32%23%24%14%6%1
420
11th to 20thDay
27%23%32%12%41
412
21st to endDay
30%19%33%15%22
420
May1st to 10thDay
34%23%27%12%31
423
11th to 20thDay
24%19%38%13%5%1
447
21st to endDay
19%13%37%22%7%1
485
June1st to 10thDay
22%12%38%19%6%2
450
11th to 20thDay
18%16%40%20%5%2
450
21st to endDay
15%15%37%23%8%2
450
July1st to 10thDay
19%8%32%28%12%1
445
11th to 20thDay
16%8%33%29%11%3
444
21st to endDay
13%8%38%32%7%1
488
August1st to 10thDay
11%10%32%33%11%2
446
11th to 20thDay
16%8%32%28%13%2
439
21st to endDay
14%10%33%26%13%5%
495
September1st to 10thDay
20%9%28%25%15%2
450
11th to 20thDay
21%12%30%19%12%7%
450
21st to endDay
23%12%30%22%9%4
450
October1st to 10thDay
29%12%25%20%10%4
450
11th to 20thDay
19%17%33%21%8%2
401
21st to endDay
28%14%32%17%9%1
396
November1st to 10thDay
22%15%33%18%9%3
365
11th to 20thDay
28%19%32%16%5%1
370
21st to endDay
26%19%30%18%6%1
370
December1st to 10thDay
25%22%35%15%3
221
11th to 20thDay
32%23%34%8%2
180
21st to endDay
25%22%36%12%42
198
January1st to 10thNight
23%18%39%18%3
760
11th to 20thNight
28%17%36%17%2
760
21st to endNight
21%18%36%21%4
836
February1st to 10thNight
24%16%36%22%2
760
11th to 20thNight
23%18%41%17%1
743
21st to endNight
26%18%33%20%3
628
March1st to 10thNight
25%16%36%18%4
760
11th to 20thNight
23%18%38%17%4
752
21st to endNight
24%18%35%19%5%
792
April1st to 10thNight
24%20%32%21%4
720
11th to 20thNight
23%19%34%19%5%
698
21st to endNight
25%16%35%21%2
540
May1st to 10thNight
28%16%32%20%4
540
11th to 20thNight
20%16%40%19%4
518
21st to endNight
21%10%34%30%5%1
389
June1st to 10thNight
21%7%36%29%7%
360
11th to 20thNight
18%6%40%30%6%
360
21st to endNight
16%6%38%35%6%
360
July1st to 10thNight
14%5%34%38%10%
350
11th to 20thNight
13%332%41%11%
348
21st to endNight
13%5%33%40%9%1
394
August1st to 10thNight
11%6%35%39%10%
495
11th to 20thNight
13%6%31%40%10%
557
21st to endNight
15%5%24%40%14%2
792
September1st to 10thNight
16%6%32%34%12%
720
11th to 20thNight
17%8%28%27%18%2
720
21st to endNight
21%8%26%32%12%2
720
October1st to 10thNight
24%11%26%25%12%2
720
11th to 20thNight
20%12%32%24%12%1
720
21st to endNight
27%14%32%22%6%1
792
November1st to 10thNight
18%14%32%26%8%1
740
11th to 20thNight
23%18%32%19%7%
760
21st to endNight
23%19%33%19%5%1
760
December1st to 10thNight
24%18%34%18%4
760
11th to 20thNight
24%18%31%23%3
760
21st to endNight
25%16%35%21%2
836
Page generated at 2024-03-15 14:01:44. Version ac07

Copyright © 2024 Attilla Danko.


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