Canfield
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Canfield clear sky chart from 2005-11-06 to 2024-01-13.

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
34%
23338
14%
74899
10%
23288
39%
23288
17%
53709

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
12%
757
10%
2459
3%
757
20%
757
8%
1990
January11th to 20thNight
14%
732
6%
2378
3%
732
18%
732
7%
1960
January21st to endNight
17%
792
9%
2574
5%
792
22%
792
8%
2102
February1st to 10thNight
15%
720
8%
2340
4%
720
21%
720
9%
1877
February11th to 20thNight
15%
702
9%
2263
3%
700
21%
700
10%
1774
February21st to endNight
15%
592
12%
1776
3%
592
24%
592
11%
1409
March1st to 10thNight
21%
720
15%
1990
7%
720
28%
720
17%
1477
March11th to 20thNight
27%
720
17%
1980
10%
720
33%
720
19%
1414
March21st to endNight
24%
792
17%
2178
9%
792
31%
792
18%
1626
April1st to 10thNight
26%
720
13%
1913
4%
720
32%
720
19%
1385
April11th to 20thNight
29%
637
16%
1701
7%
637
35%
637
22%
1217
April21st to endNight
30%
540
17%
1620
7%
540
37%
540
22%
1112
May1st to 10thNight
35%
540
12%
1620
7%
540
40%
540
18%
1178
May11th to 20thNight
42%
531
15%
1592
10%
531
47%
531
22%
1096
May21st to endNight
56%
475
17%
1638
15%
475
60%
475
29%
979
June1st to 10thNight
50%
360
16%
1440
18%
360
56%
360
22%
861
June11th to 20thNight
52%
360
18%
1440
21%
360
59%
360
22%
848
June21st to endNight
51%
360
17%
1440
20%
360
57%
360
22%
855
July1st to 10thNight
63%
452
14%
1502
15%
452
66%
452
27%
926
July11th to 20thNight
61%
522
17%
1566
14%
522
64%
522
34%
933
July21st to endNight
62%
591
15%
1672
13%
558
63%
558
28%
1078
August1st to 10thNight
65%
537
19%
1600
16%
534
67%
534
31%
974
August11th to 20thNight
62%
534
19%
1598
15%
534
64%
534
30%
1001
August21st to endNight
58%
652
21%
1840
14%
652
61%
652
32%
1154
September1st to 10thNight
56%
720
22%
1838
14%
720
60%
720
33%
1198
September11th to 20thNight
65%
720
26%
1980
20%
720
67%
720
36%
1183
September21st to endNight
45%
720
21%
1980
15%
720
50%
720
26%
1319
October1st to 10thNight
46%
720
18%
2132
16%
720
49%
720
28%
1359
October11th to 20thNight
32%
720
15%
2160
10%
720
40%
720
19%
1498
October21st to endNight
27%
792
18%
2376
12%
792
35%
792
17%
1724
November1st to 10thNight
37%
740
21%
2353
15%
740
45%
740
24%
1517
November11th to 20thNight
23%
760
15%
2555
10%
760
30%
760
14%
1858
November21st to endNight
23%
760
12%
2660
8%
760
31%
760
12%
1996
December1st to 10thNight
16%
760
6%
2660
4%
760
20%
760
8%
2148
December11th to 20thNight
17%
759
8%
3261
4%
759
22%
759
6%
2555
December21st to endNight
15%
829
4%
4824
3%
817
21%
817
3%
4128

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%10%47%6%35%5%5%7%31%
74600
Night
17%10%47%6%35%45%6%33%
75143
TransparencyDay
52%7%12%18%10%1
74321
Night
51%7%12%18%11%2
74941
SeeingDay
22%13%28%21%12%5%
13508
Night
22%11%27%27%12%1
23352

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
17%16%8%11%8%44445%18%
1706
11th to 20thDay
19%19%8%11%7%44345%16%
1644
21st to endDay
17%18%9%12%9%34345%14%
1782
February1st to 10thDay
20%17%6%10%9%35%33420%
1620
11th to 20thDay
16%14%7%13%9%345%45%19%
1582
21st to endDay
20%14%5%10%7%3445%5%24%
1480
March1st to 10thDay
18%11%6%8%6%2445%6%29%
1968
11th to 20thDay
19%13%5%8%6%35%447%29%
1980
21st to endDay
21%12%5%9%6%34345%27%
2178
April1st to 10thDay
16%12%47%6%35%448%32%
2047
11th to 20thDay
19%11%36%5%35%5%5%6%32%
2224
21st to endDay
22%10%46%5%3335%6%33%
2340
May1st to 10thDay
19%9%37%6%46%6%5%7%29%
2340
11th to 20thDay
21%7%36%6%45%5%6%6%32%
2301
21st to endDay
11%5%35%6%5%6%6%7%9%38%
2633
June1st to 10thDay
16%6%35%7%35%5%7%8%34%
2520
11th to 20thDay
15%6%36%6%46%5%5%8%37%
2520
21st to endDay
13%425%5%45%6%7%10%38%
2520
July1st to 10thDay
12%6%36%6%35%5%5%9%42%
2408
11th to 20thDay
13%5%35%6%36%5%6%9%39%
2340
21st to endDay
12%5%26%6%46%6%7%9%37%
2547
August1st to 10thDay
10%6%35%6%46%7%6%9%37%
2327
11th to 20thDay
12%6%36%7%46%6%7%10%33%
2303
21st to endDay
11%5%36%6%46%5%7%9%38%
2496
September1st to 10thDay
15%6%25%5%35%45%7%43%
2120
11th to 20thDay
12%5%35%5%346%6%8%42%
1980
21st to endDay
18%7%37%5%3445%7%38%
1980
October1st to 10thDay
16%7%37%6%345%6%7%37%
1828
11th to 20thDay
20%9%36%7%4445%5%33%
1800
21st to endDay
24%11%47%5%44347%28%
1980
November1st to 10thDay
11%8%47%6%3445%7%40%
1722
11th to 20thDay
16%15%46%5%35%446%30%
1621
21st to endDay
17%15%7%10%5%445%5%6%23%
1520
December1st to 10thDay
21%17%8%10%6%345%5%417%
1520
11th to 20thDay
18%17%9%12%5%35%45%6%17%
1910
21st to endDay
27%22%8%9%6%3433412%
2813
January1st to 10thNight
18%16%7%11%7%44445%21%
2459
11th to 20thNight
20%16%6%11%7%35%5%4418%
2378
21st to endNight
16%17%8%12%7%45%44419%
2574
February1st to 10thNight
22%12%6%9%8%45%446%21%
2340
11th to 20thNight
18%13%6%11%7%45%35%5%22%
2261
21st to endNight
21%12%7%9%6%34445%24%
1776
March1st to 10thNight
18%11%5%8%5%35%446%32%
1990
11th to 20thNight
19%10%47%5%34447%34%
1980
21st to endNight
19%10%5%8%6%24445%33%
2178
April1st to 10thNight
16%11%5%6%5%3445%6%34%
1913
11th to 20thNight
16%9%47%5%45%46%7%34%
1701
21st to endNight
16%9%36%5%3445%8%36%
1620
May1st to 10thNight
19%9%36%6%46%45%7%31%
1620
11th to 20thNight
16%6%36%5%345%6%9%36%
1592
21st to endNight
9%425%5%36%47%12%44%
1637
June1st to 10thNight
10%5%36%7%45%5%6%7%44%
1440
11th to 20thNight
11%5%36%6%35%46%9%43%
1440
21st to endNight
11%425%5%35%6%7%9%43%
1440
July1st to 10thNight
8%426%6%45%5%6%7%48%
1547
11th to 20thNight
9%4245%3447%10%48%
1620
21st to endNight
11%5%25%6%45%6%8%8%40%
1771
August1st to 10thNight
9%435%435%6%5%8%47%
1611
11th to 20thNight
11%5%26%6%3445%8%46%
1598
21st to endNight
11%325%5%345%7%7%47%
1840
September1st to 10thNight
13%5%25%42445%7%49%
1838
11th to 20thNight
12%4244335%5%8%51%
1980
21st to endNight
16%6%35%435%5%5%8%41%
1980
October1st to 10thNight
15%5%245%35%45%7%44%
2132
11th to 20thNight
18%7%36%6%45%5%5%7%35%
2160
21st to endNight
25%8%26%5%345%45%33%
2376
November1st to 10thNight
15%9%24435%45%7%42%
2353
11th to 20thNight
17%13%5%7%6%35%445%31%
2555
21st to endNight
20%15%47%5%35%446%28%
2660
December1st to 10thNight
21%16%7%9%6%34445%20%
2660
11th to 20thNight
17%19%7%10%6%3445%5%21%
3285
21st to endNight
26%19%8%8%6%3445%413%
4838

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
69%6%10%11%4
1707
11th to 20thDay
73%5%11%10%2
1644
21st to endDay
73%5%8%10%31
1782
February1st to 10thDay
70%49%11%5%
1620
11th to 20thDay
67%6%9%12%7%
1591
21st to endDay
62%6%10%14%7%1
1480
March1st to 10thDay
55%7%13%19%6%
1968
11th to 20thDay
56%6%9%17%9%1
1980
21st to endDay
59%5%8%16%10%1
2178
April1st to 10thDay
51%6%12%18%12%1
2047
11th to 20thDay
51%7%11%16%13%3
2224
21st to endDay
52%6%11%19%9%2
2340
May1st to 10thDay
53%9%11%16%9%1
2340
11th to 20thDay
51%8%11%15%12%2
2305
21st to endDay
40%10%15%22%11%2
2633
June1st to 10thDay
46%8%13%21%11%1
2520
11th to 20thDay
44%9%13%20%12%1
2520
21st to endDay
39%9%14%24%13%1
2520
July1st to 10thDay
39%9%13%23%13%3
2343
11th to 20thDay
40%8%13%23%14%1
2271
21st to endDay
40%9%15%22%13%1
2405
August1st to 10thDay
41%10%16%24%10%
2314
11th to 20thDay
42%11%15%21%9%2
2303
21st to endDay
40%10%14%21%12%3
2496
September1st to 10thDay
41%7%12%20%16%3
2120
11th to 20thDay
37%9%14%24%15%1
1980
21st to endDay
45%8%12%22%12%1
1980
October1st to 10thDay
44%7%12%21%15%1
1828
11th to 20thDay
51%7%13%19%9%1
1800
21st to endDay
56%7%12%15%9%1
1980
November1st to 10thDay
44%7%12%20%15%2
1722
11th to 20thDay
55%7%11%17%8%3
1621
21st to endDay
61%7%11%15%6%1
1520
December1st to 10thDay
70%6%11%11%3
1520
11th to 20thDay
67%7%9%14%3
1906
21st to endDay
78%5%9%7%2
2813
January1st to 10thNight
66%6%10%13%5%
2459
11th to 20thNight
69%6%10%12%31
2378
21st to endNight
69%5%9%14%41
2574
February1st to 10thNight
66%6%10%14%4
2340
11th to 20thNight
64%5%11%14%6%
2263
21st to endNight
63%6%8%14%8%1
1776
March1st to 10thNight
54%5%10%20%10%1
1990
11th to 20thNight
49%6%13%20%10%2
1980
21st to endNight
53%7%7%18%13%2
2178
April1st to 10thNight
50%6%11%18%13%2
1913
11th to 20thNight
48%7%12%16%15%3
1701
21st to endNight
45%7%13%18%14%2
1620
May1st to 10thNight
51%8%9%17%12%3
1620
11th to 20thNight
45%9%11%17%15%3
1593
21st to endNight
34%9%17%25%14%2
1638
June1st to 10thNight
37%9%13%23%15%2
1440
11th to 20thNight
37%7%14%23%16%2
1440
21st to endNight
36%10%12%23%17%1
1440
July1st to 10thNight
35%9%12%22%18%3
1502
11th to 20thNight
29%10%15%25%18%2
1566
21st to endNight
36%10%16%20%14%3
1672
August1st to 10thNight
32%9%14%28%17%1
1600
11th to 20thNight
35%9%15%25%14%2
1598
21st to endNight
32%10%12%26%16%4
1840
September1st to 10thNight
35%7%13%23%18%5%
1838
11th to 20thNight
30%8%15%25%21%2
1980
21st to endNight
41%6%13%21%17%1
1980
October1st to 10thNight
38%7%15%22%17%2
2132
11th to 20thNight
47%7%12%21%11%1
2160
21st to endNight
52%6%10%20%10%2
2376
November1st to 10thNight
41%7%11%23%15%3
2353
11th to 20thNight
55%6%10%18%8%3
2555
21st to endNight
58%7%12%18%5%1
2660
December1st to 10thNight
67%7%11%11%4
2660
11th to 20thNight
65%7%11%14%3
3288
21st to endNight
73%8%9%8%1
4838

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
33%22%31%11%4
270
11th to 20thDay
31%21%35%10%3
248
21st to endDay
27%27%33%9%31
264
February1st to 10thDay
33%20%40%7%
240
11th to 20thDay
32%26%32%10%1
240
21st to endDay
35%22%34%9%
198
March1st to 10thDay
28%17%36%15%4
408
11th to 20thDay
30%15%34%14%5%2
420
21st to endDay
33%18%26%18%41
462
April1st to 10thDay
23%23%29%15%8%1
420
11th to 20thDay
27%14%27%17%10%4
412
21st to endDay
28%16%31%18%6%2
420
May1st to 10thDay
27%18%24%19%9%3
423
11th to 20thDay
23%11%31%25%7%3
447
21st to endDay
15%8%27%26%17%6%
485
June1st to 10thDay
15%10%31%29%11%4
450
11th to 20thDay
18%10%25%26%17%4
450
21st to endDay
14%10%33%25%14%5%
450
July1st to 10thDay
13%420%28%23%13%
445
11th to 20thDay
12%7%25%29%19%8%
444
21st to endDay
13%327%28%19%9%
488
August1st to 10thDay
11%6%20%31%21%11%
446
11th to 20thDay
15%5%22%25%21%12%
439
21st to endDay
11%6%23%28%21%11%
495
September1st to 10thDay
15%8%20%26%22%9%
450
11th to 20thDay
10%420%31%25%10%
450
21st to endDay
22%10%23%23%14%7%
450
October1st to 10thDay
14%10%24%27%18%6%
450
11th to 20thDay
22%15%36%18%8%1
450
21st to endDay
32%15%29%19%5%
495
November1st to 10thDay
18%23%31%16%11%2
320
11th to 20thDay
31%19%25%17%7%2
228
21st to endDay
23%22%43%12%1
180
December1st to 10thDay
33%24%26%11%32
180
11th to 20thDay
30%19%37%10%4
180
21st to endDay
37%21%27%12%2
211
January1st to 10thNight
27%21%32%16%4
760
11th to 20thNight
30%17%32%15%4
732
21st to endNight
27%18%30%21%4
792
February1st to 10thNight
30%16%31%20%2
720
11th to 20thNight
28%16%36%18%2
703
21st to endNight
30%15%33%19%3
592
March1st to 10thNight
25%16%34%23%2
720
11th to 20thNight
24%16%30%23%6%1
720
21st to endNight
25%14%31%24%5%1
792
April1st to 10thNight
24%14%29%26%6%
720
11th to 20thNight
22%12%33%23%9%1
637
21st to endNight
20%9%35%28%7%
540
May1st to 10thNight
22%9%26%31%11%1
540
11th to 20thNight
21%6%25%35%12%1
531
21st to endNight
11%325%37%21%3
477
June1st to 10thNight
12%227%44%15%1
360
11th to 20thNight
10%6%24%46%14%1
360
21st to endNight
11%426%41%19%1
360
July1st to 10thNight
7%315%42%27%6%
452
11th to 20thNight
11%220%37%26%4
522
21st to endNight
13%115%42%26%3
591
August1st to 10thNight
11%213%44%28%2
537
11th to 20thNight
14%211%37%29%5%
534
21st to endNight
13%221%31%28%5%
652
September1st to 10thNight
15%5%17%33%26%5%
720
11th to 20thNight
13%314%36%30%5%
720
21st to endNight
18%8%22%27%20%5%
720
October1st to 10thNight
17%7%25%28%20%3
720
11th to 20thNight
21%13%29%27%9%1
720
21st to endNight
30%10%27%26%6%
792
November1st to 10thNight
20%10%29%29%11%
740
11th to 20thNight
26%16%30%20%7%1
760
21st to endNight
29%16%28%22%5%1
760
December1st to 10thNight
32%18%27%18%5%
760
11th to 20thNight
27%19%30%20%4
760
21st to endNight
31%16%31%20%2
836
Page generated at 2024-01-10 19:35:25. Version ac07

Copyright 2024 Attilla Danko


Canfield Clear Sky Chart |Charts Home