Massena
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Massena clear sky chart from 2005-11-05 to 2019-06-24.

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%
16917
12%
53998
7%
16886
32%
16886
15%
39461

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
12%
840
7%
2926
2%
836
18%
836
6%
2411
January16th to endNight
16%
896
8%
3105
4%
896
21%
896
8%
2446
February1st to 15thNight
12%
824
8%
2677
2%
821
19%
821
7%
2183
February16th to endNight
18%
735
10%
2232
4%
735
27%
735
11%
1719
March1st to 15thNight
18%
840
12%
2487
6%
840
25%
840
13%
1917
March16th to endNight
27%
896
18%
2346
8%
896
34%
896
20%
1701
April1st to 15thNight
20%
838
15%
2096
5%
838
26%
838
17%
1595
April16th to endNight
25%
769
15%
2015
5%
769
32%
769
21%
1444
May1st to 15thNight
29%
424
17%
1684
14%
424
39%
424
15%
1132
May16th to endNight
30%
438
13%
1753
8%
438
42%
438
18%
1092
June1st to 15thNight
35%
420
10%
1680
12%
420
41%
420
13%
1158
June16th to endNight
38%
406
9%
1625
12%
406
43%
406
18%
1015
July1st to 15thNight
49%
370
15%
1480
21%
370
57%
370
27%
804
July16th to endNight
48%
408
13%
1546
14%
386
53%
386
24%
902
August1st to 15thNight
45%
442
14%
1583
11%
440
50%
440
20%
1033
August16th to endNight
46%
806
19%
2048
10%
806
50%
806
35%
1316
September1st to 15thNight
45%
780
17%
1950
8%
780
47%
780
29%
1344
September16th to endNight
44%
777
22%
2105
15%
777
48%
777
29%
1371
October1st to 15thNight
30%
780
16%
2340
10%
780
37%
780
18%
1661
October16th to endNight
22%
832
9%
2623
5%
832
28%
832
11%
2004
November1st to 15thNight
23%
820
15%
2681
10%
820
30%
820
14%
1941
November16th to endNight
19%
840
9%
2940
7%
840
24%
840
8%
2285
December1st to 15thNight
14%
840
6%
2940
2%
840
20%
840
6%
2409
December16th to endNight
13%
896
7%
3136
3%
896
18%
896
6%
2578

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
18%9%36%5%34446%31%
54831
Night
19%10%47%5%34445%30%
54167
Cloud CoverDay
19%9%36%5%34446%31%
54840
Night
19%10%47%5%34445%29%
54173
TransparencyDay
52%5%12%19%9%1
54518
Night
55%5%11%17%8%
53998
SeeingDay
27%14%28%18%8%2
7706
Night
27%13%28%22%8%
16918

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
21%17%6%9%7%35%33317%
1672
16th to endDay
15%16%5%10%8%35%445%19%
1820
February1st to 15thDay
16%13%5%12%7%46%44419%
1845
16th to endDay
18%15%5%8%7%34235%24%
1813
March1st to 15thDay
19%14%5%8%7%3433325%
2121
16th to endDay
18%8%35%423335%38%
2581
April1st to 15thDay
22%10%45%6%24335%30%
2512
16th to endDay
22%8%35%423345%35%
2558
May1st to 15thDay
19%7%26%5%34446%35%
2931
16th to endDay
16%6%26%5%345%5%7%36%
3066
June1st to 15thDay
22%5%25%5%3445%6%32%
2940
16th to endDay
19%435%5%35%5%5%8%33%
2842
July1st to 15thDay
12%5%245%345%6%8%41%
2730
16th to endDay
12%5%35%5%35%7%7%8%36%
2878
August1st to 15thDay
12%6%36%6%46%5%7%7%33%
2619
16th to endDay
10%415%5%35%5%6%7%42%
2493
September1st to 15thDay
17%5%234345%46%41%
2340
16th to endDay
15%42442335%6%46%
2182
October1st to 15thDay
22%6%26%6%35%45%6%31%
1950
16th to endDay
25%11%37%5%3433426%
1951
November1st to 15thDay
17%9%46%6%35%45%6%29%
1835
16th to endDay
22%14%47%7%3434423%
1680
December1st to 15thDay
22%16%5%9%7%35%44416%
1680
16th to endDay
25%16%5%7%5%3443418%
1792
January1st to 15thNight
20%18%6%10%6%2443417%
2926
16th to endNight
14%16%6%10%7%44345%21%
3105
February1st to 15thNight
16%15%7%13%7%35%33419%
2675
16th to endNight
18%13%48%6%2434427%
2232
March1st to 15thNight
20%14%5%7%5%3433427%
2474
16th to endNight
19%10%36%5%2323437%
2346
April1st to 15thNight
24%9%36%6%23335%31%
2096
16th to endNight
21%9%24423345%36%
2015
May1st to 15thNight
20%7%35%5%34446%34%
1684
16th to endNight
16%6%25%42446%8%38%
1751
June1st to 15thNight
22%6%35%5%35%45%7%30%
1680
16th to endNight
15%7%3442446%9%36%
1625
July1st to 15thNight
10%2135%26%46%10%44%
1560
16th to endNight
10%415%4346%7%8%42%
1642
August1st to 15thNight
12%6%27%5%2446%8%37%
1593
16th to endNight
13%42442335%6%47%
2048
September1st to 15thNight
16%4245%335%5%6%41%
1950
16th to endNight
16%424434446%46%
2105
October1st to 15thNight
20%7%25%43445%6%34%
2340
16th to endNight
26%10%37%5%33445%25%
2623
November1st to 15thNight
22%10%36%5%2435%5%31%
2681
16th to endNight
22%13%5%8%5%24445%23%
2940
December1st to 15thNight
22%16%5%9%6%345%35%17%
2940
16th to endNight
23%17%5%8%7%3333418%
3136

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
21%17%5%11%6%45%32417%
1672
16th to endDay
15%16%6%10%7%45%445%19%
1820
February1st to 15thDay
16%14%5%12%8%45%44418%
1845
16th to endDay
18%16%5%9%6%3433423%
1813
March1st to 15thDay
20%15%5%9%7%2434324%
2131
16th to endDay
20%9%36%423235%38%
2580
April1st to 15thDay
23%10%45%6%33335%30%
2512
16th to endDay
23%8%35%423445%35%
2558
May1st to 15thDay
19%7%35%5%345%46%34%
2931
16th to endDay
17%6%25%5%3445%8%35%
3066
June1st to 15thDay
24%5%25%5%3445%6%31%
2940
16th to endDay
19%5%345%35%6%6%7%32%
2842
July1st to 15thDay
12%5%345%25%5%5%8%41%
2730
16th to endDay
12%5%35%5%35%6%6%9%35%
2878
August1st to 15thDay
13%6%26%6%45%6%6%8%33%
2619
16th to endDay
11%4245%35%6%6%8%41%
2493
September1st to 15thDay
18%5%1442345%6%41%
2340
16th to endDay
15%5%14323447%45%
2182
October1st to 15thDay
22%6%27%6%345%46%30%
1950
16th to endDay
27%10%46%5%34325%26%
1951
November1st to 15thDay
18%10%36%6%3445%7%29%
1835
16th to endDay
22%14%5%8%6%3423424%
1680
December1st to 15thDay
23%17%6%9%7%2344416%
1680
16th to endDay
26%17%5%7%6%33335%17%
1792
January1st to 15thNight
20%18%6%11%6%3443417%
2926
16th to endNight
15%17%6%9%7%45%34421%
3105
February1st to 15thNight
16%15%7%13%8%3434318%
2668
16th to endNight
18%13%5%9%7%34345%25%
2232
March1st to 15thNight
21%14%5%7%6%2433327%
2487
16th to endNight
21%9%35%5%2333337%
2346
April1st to 15thNight
24%9%47%5%23345%30%
2096
16th to endNight
22%8%24423435%36%
2015
May1st to 15thNight
22%7%36%4245%45%34%
1684
16th to endNight
17%5%25%4245%47%38%
1751
June1st to 15thNight
23%6%34435%45%7%30%
1680
16th to endNight
16%6%24425%5%6%9%36%
1625
July1st to 15thNight
10%3135%26%5%6%10%44%
1560
16th to endNight
10%5%245%345%7%8%42%
1642
August1st to 15thNight
12%6%35%5%345%5%8%37%
1593
16th to endNight
12%5%25%42435%7%46%
2048
September1st to 15thNight
16%4345%33446%42%
1950
16th to endNight
16%42442335%7%45%
2105
October1st to 15thNight
20%7%35%43445%5%34%
2340
16th to endNight
27%10%36%5%33345%24%
2623
November1st to 15thNight
22%11%26%423445%30%
2681
16th to endNight
24%13%5%7%5%2434423%
2940
December1st to 15thNight
22%18%5%9%6%3444416%
2940
16th to endNight
23%16%6%8%6%3443417%
3136

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
72%37%10%4
1673
16th to endDay
65%5%11%11%4
1820
February1st to 15thDay
68%49%14%2
1847
16th to endDay
63%311%12%8%
1813
March1st to 15thDay
64%410%13%6%
2131
16th to endDay
49%39%18%15%4
2581
April1st to 15thDay
57%37%18%11%1
2512
16th to endDay
51%39%18%14%3
2558
May1st to 15thDay
50%5%9%19%13%1
2931
16th to endDay
46%6%13%20%12%1
3070
June1st to 15thDay
51%6%10%19%10%
2940
16th to endDay
47%7%11%21%10%1
2842
July1st to 15thDay
38%5%14%28%12%
2581
16th to endDay
41%9%17%23%8%
2711
August1st to 15thDay
46%9%17%19%7%
2605
16th to endDay
37%6%16%27%10%
2493
September1st to 15thDay
41%5%13%25%13%
2340
16th to endDay
38%5%13%31%10%
2182
October1st to 15thDay
52%414%19%8%
1950
16th to endDay
61%413%14%5%
1951
November1st to 15thDay
54%5%14%17%7%
1835
16th to endDay
65%410%13%5%
1680
December1st to 15thDay
70%5%11%10%1
1680
16th to endDay
70%5%9%10%4
1792
January1st to 15thNight
70%5%10%9%4
2926
16th to endNight
65%410%13%5%
3105
February1st to 15thNight
70%39%13%3
2677
16th to endNight
60%410%15%8%
2232
March1st to 15thNight
61%311%17%5%
2487
16th to endNight
51%38%18%13%3
2346
April1st to 15thNight
56%38%19%11%
2096
16th to endNight
49%48%18%15%3
2015
May1st to 15thNight
50%6%7%17%15%3
1684
16th to endNight
43%6%14%20%13%1
1753
June1st to 15thNight
52%6%12%15%11%1
1680
16th to endNight
42%7%13%21%14%
1625
July1st to 15thNight
32%6%15%29%15%1
1480
16th to endNight
36%6%16%23%15%
1546
August1st to 15thNight
43%7%17%20%10%
1583
16th to endNight
36%414%30%13%
2048
September1st to 15thNight
41%6%11%27%11%
1950
16th to endNight
38%5%11%32%11%
2105
October1st to 15thNight
50%5%11%22%9%
2340
16th to endNight
59%5%15%15%3
2623
November1st to 15thNight
54%5%13%15%8%1
2681
16th to endNight
63%5%11%13%4
2940
December1st to 15thNight
69%5%12%11%2
2940
16th to endNight
70%410%10%3
3136

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
34%15%27%16%6%
120
16th to endDay
32%23%31%11%
136
February1st to 15thDay
49%23%24%2
180
16th to endDay
35%20%27%14%1
316
March1st to 15thDay
34%15%30%14%4
390
16th to endDay
29%19%25%15%8%1
416
April1st to 15thDay
38%16%27%13%31
390
16th to endDay
34%13%26%14%8%2
379
May1st to 15thDay
31%15%26%15%8%1
408
16th to endDay
23%17%32%16%8%
459
June1st to 15thDay
30%12%28%21%5%1
435
16th to endDay
22%12%34%22%7%1
407
July1st to 15thDay
15%7%29%30%14%2
365
16th to endDay
16%6%33%28%11%3
390
August1st to 15thDay
17%8%29%27%12%4
358
16th to endDay
12%7%31%27%12%8%
396
September1st to 15thDay
18%7%26%22%14%11%
375
16th to endDay
16%12%26%21%14%7%
374
October1st to 15thDay
25%15%28%16%10%3
375
16th to endDay
37%18%22%16%4
360
November1st to 15thDay
29%16%26%18%7%1
309
16th to endDay
43%16%23%14%2
120
December1st to 15thDay
30%21%25%16%4
120
16th to endDay
46%19%25%7%2
128
January1st to 15thNight
32%18%29%15%3
840
16th to endNight
26%20%30%18%3
896
February1st to 15thNight
28%19%30%19%1
824
16th to endNight
27%16%32%19%3
735
March1st to 15thNight
32%16%29%18%3
840
16th to endNight
25%14%26%25%7%
896
April1st to 15thNight
31%15%28%21%3
838
16th to endNight
29%13%28%20%7%
769
May1st to 15thNight
27%8%30%24%8%1
424
16th to endNight
19%8%36%27%7%
439
June1st to 15thNight
27%8%23%33%6%
420
16th to endNight
17%8%29%31%11%1
406
July1st to 15thNight
9%5%28%40%15%
370
16th to endNight
12%430%37%12%1
408
August1st to 15thNight
17%324%35%18%1
442
16th to endNight
15%428%31%18%1
806
September1st to 15thNight
20%5%24%30%16%2
780
16th to endNight
18%9%24%23%21%2
777
October1st to 15thNight
25%11%28%22%12%
780
16th to endNight
35%13%24%20%5%
832
November1st to 15thNight
30%13%27%19%8%
820
16th to endNight
33%17%23%17%7%
840
December1st to 15thNight
34%20%24%17%3
840
16th to endNight
36%14%29%15%2
896
Page generated at 2019-06-24 20:41:27. Version ac04

Copyright 2019 A. Danko


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