Mattawa
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mattawa clear sky chart from 2005-11-05 to 2017-09-21.

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
27%
14838
12%
46706
7%
14810
32%
14810
15%
34489

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
11%
838
5%
2625
3%
835
14%
835
6%
2262
January16th to endNight
21%
768
10%
2568
6%
768
26%
768
10%
2046
February1st to 15thNight
17%
702
8%
2287
4%
701
23%
701
9%
1819
February16th to endNight
18%
631
10%
2039
4%
631
25%
631
10%
1613
March1st to 15thNight
18%
720
12%
2005
5%
720
24%
720
13%
1553
March16th to endNight
30%
768
19%
2103
10%
768
37%
768
22%
1460
April1st to 15thNight
24%
718
15%
1796
6%
718
30%
718
19%
1351
April16th to endNight
30%
555
17%
1635
9%
555
37%
555
20%
1159
May1st to 15thNight
32%
402
17%
1482
13%
402
42%
402
19%
954
May16th to endNight
33%
374
12%
1497
10%
374
44%
374
18%
940
June1st to 15thNight
35%
360
7%
1347
7%
360
39%
360
15%
918
June16th to endNight
35%
360
9%
1260
6%
360
41%
360
19%
833
July1st to 15thNight
45%
340
15%
1194
16%
340
49%
340
30%
676
July16th to endNight
46%
376
13%
1418
15%
354
52%
354
24%
835
August1st to 15thNight
45%
533
12%
1604
9%
531
49%
531
25%
1076
August16th to endNight
48%
621
18%
1767
10%
621
53%
621
29%
1114
September1st to 15thNight
40%
720
15%
1800
7%
720
43%
720
31%
1207
September16th to endNight
42%
681
18%
1895
11%
681
46%
681
30%
1230
October1st to 15thNight
27%
660
16%
1980
10%
660
35%
660
17%
1416
October16th to endNight
20%
704
9%
2133
6%
704
25%
704
11%
1697
November1st to 15thNight
24%
700
14%
2444
12%
700
30%
700
13%
1783
November16th to endNight
19%
720
8%
2520
6%
720
23%
720
8%
2049
December1st to 15thNight
13%
720
6%
2520
2%
720
18%
720
6%
2113
December16th to endNight
11%
867
7%
2787
3%
867
15%
867
6%
2385

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
19%11%47%5%34446%28%
48164
Night
18%12%5%7%6%34345%28%
46866
TransparencyDay
57%310%19%8%
47842
Night
57%310%18%8%
46706
SeeingDay
25%11%28%21%9%3
5749
Night
25%11%28%24%9%
14843

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
18%18%7%10%8%3433317%
1309
16th to endDay
14%15%8%10%8%45%445%17%
1654
February1st to 15thDay
9%19%7%12%11%46%44416%
1575
16th to endDay
16%18%6%10%8%3433420%
1434
March1st to 15thDay
16%15%6%9%5%3434426%
1942
16th to endDay
14%9%47%6%2443436%
2121
April1st to 15thDay
23%12%46%413345%29%
2152
16th to endDay
21%10%35%42333437%
2334
May1st to 15thDay
22%9%36%5%2445%6%30%
2469
16th to endDay
18%8%45%5%34447%34%
2618
June1st to 15thDay
23%7%36%5%35%45%6%28%
2610
16th to endDay
18%5%35%5%46%5%6%7%30%
2700
July1st to 15thDay
17%5%25%5%35%45%8%35%
2694
16th to endDay
16%5%25%5%445%6%9%33%
2654
August1st to 15thDay
18%7%36%5%45%447%31%
2344
16th to endDay
15%8%36%7%345%5%7%32%
2423
September1st to 15thDay
21%6%35%5%2445%7%34%
2160
16th to endDay
23%6%34423336%37%
1858
October1st to 15thDay
22%12%36%423346%28%
1650
16th to endDay
32%15%46%5%2333418%
1738
November1st to 15thDay
21%13%5%7%433336%27%
1414
16th to endDay
25%20%6%8%5%2432316%
1440
December1st to 15thDay
20%21%7%11%7%3433412%
1440
16th to endDay
20%21%9%13%5%3323312%
1431
January1st to 15thNight
19%17%8%11%9%4443412%
2625
16th to endNight
13%16%7%11%7%45%44418%
2568
February1st to 15thNight
11%13%8%12%10%5%5%45%418%
2285
16th to endNight
16%16%6%10%6%45%43321%
2039
March1st to 15thNight
18%14%6%9%5%3443426%
1993
16th to endNight
15%10%47%6%23235%38%
2103
April1st to 15thNight
22%12%45%5%2334432%
1796
16th to endNight
21%9%35%434435%34%
1635
May1st to 15thNight
20%7%4442435%5%36%
1482
16th to endNight
17%6%36%424447%36%
1495
June1st to 15thNight
18%7%36%5%45%35%5%32%
1347
16th to endNight
14%7%26%5%35%6%6%6%35%
1260
July1st to 15thNight
13%32443435%10%43%
1264
16th to endNight
10%4345%35%47%6%41%
1514
August1st to 15thNight
15%5%35%4346%6%7%36%
1614
16th to endNight
12%5%345%2446%8%42%
1767
September1st to 15thNight
18%5%24423345%44%
1800
16th to endNight
19%6%2432335%6%43%
1895
October1st to 15thNight
22%9%36%5%24335%33%
1980
16th to endNight
30%13%36%42434422%
2133
November1st to 15thNight
20%14%46%5%34335%28%
2444
16th to endNight
25%16%5%8%6%2433319%
2520
December1st to 15thNight
21%21%8%9%7%3232415%
2520
16th to endNight
22%18%8%11%6%3432314%
2787

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
71%37%12%5%
1310
16th to endDay
68%48%13%4
1654
February1st to 15thDay
71%27%12%5%
1577
16th to endDay
68%26%14%8%
1434
March1st to 15thDay
61%39%17%7%
1953
16th to endDay
50%38%19%15%3
2121
April1st to 15thDay
57%27%18%11%2
2152
16th to endDay
51%26%23%14%1
2334
May1st to 15thDay
54%38%18%13%1
2469
16th to endDay
49%411%20%12%2
2622
June1st to 15thDay
55%310%20%9%
2610
16th to endDay
48%412%22%9%1
2700
July1st to 15thDay
44%411%28%10%1
2535
16th to endDay
47%412%25%9%
2487
August1st to 15thDay
51%413%21%9%
2330
16th to endDay
48%413%25%6%
2423
September1st to 15thDay
49%413%23%9%
2160
16th to endDay
49%313%28%5%
1858
October1st to 15thDay
57%211%18%9%
1650
16th to endDay
70%38%12%4
1738
November1st to 15thDay
59%314%15%7%
1414
16th to endDay
73%29%9%3
1440
December1st to 15thDay
76%29%10%1
1440
16th to endDay
79%15%10%3
1431
January1st to 15thNight
76%37%8%3
2625
16th to endNight
67%37%15%5%
2568
February1st to 15thNight
68%210%14%4
2287
16th to endNight
67%27%15%5%
2039
March1st to 15thNight
62%210%16%7%
2005
16th to endNight
49%29%20%15%2
2103
April1st to 15thNight
55%26%20%12%1
1796
16th to endNight
51%46%19%15%2
1635
May1st to 15thNight
48%29%21%14%2
1482
16th to endNight
45%413%21%12%2
1497
June1st to 15thNight
52%311%20%10%
1347
16th to endNight
46%6%12%23%10%1
1260
July1st to 15thNight
35%315%28%15%1
1194
16th to endNight
40%416%28%9%
1418
August1st to 15thNight
42%7%17%23%10%
1604
16th to endNight
38%5%17%28%9%
1767
September1st to 15thNight
42%317%26%10%
1800
16th to endNight
41%315%32%6%
1895
October1st to 15thNight
54%211%22%9%
1980
16th to endNight
65%410%14%5%
2133
November1st to 15thNight
58%312%17%7%
2444
16th to endNight
70%310%11%3
2520
December1st to 15thNight
74%28%11%3
2520
16th to endNight
76%26%9%4
2787

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
23%23%40%11%1
60
16th to endDay
30%13%29%19%5%1
84
February1st to 15thDay
28%17%41%10%2
90
16th to endDay
41%12%35%8%1
93
March1st to 15thDay
29%14%34%17%31
270
16th to endDay
20%14%34%18%10%2
288
April1st to 15thDay
28%17%27%19%42
270
16th to endDay
27%15%28%12%11%4
270
May1st to 15thDay
34%7%22%20%10%3
288
16th to endDay
21%16%32%16%9%3
331
June1st to 15thDay
29%11%24%24%8%
405
16th to endDay
19%13%30%25%9%1
495
July1st to 15thDay
16%11%30%29%10%1
469
16th to endDay
15%7%29%30%12%3
326
August1st to 15thDay
23%224%28%11%8%
313
16th to endDay
18%8%26%26%12%7%
332
September1st to 15thDay
26%6%23%21%13%9%
315
16th to endDay
25%7%26%23%12%5%
275
October1st to 15thDay
28%11%27%20%9%2
255
16th to endDay
38%12%25%16%6%
268
November1st to 15thDay
27%14%36%13%7%
68
16th to endDay
40%16%28%13%1
60
December1st to 15thDay
30%16%41%8%3
60
16th to endDay
32%25%34%7%
64
January1st to 15thNight
30%16%30%17%4
840
16th to endNight
20%11%36%22%8%
768
February1st to 15thNight
19%16%35%21%6%
704
16th to endNight
25%13%34%21%4
631
March1st to 15thNight
27%18%30%20%3
720
16th to endNight
21%12%29%25%9%1
768
April1st to 15thNight
27%14%28%23%5%
718
16th to endNight
27%10%28%24%9%
555
May1st to 15thNight
26%7%28%27%9%
402
16th to endNight
21%8%30%28%10%
375
June1st to 15thNight
22%7%26%32%10%
360
16th to endNight
17%8%29%33%10%
360
July1st to 15thNight
13%332%35%14%
340
16th to endNight
11%5%28%36%15%1
376
August1st to 15thNight
17%6%21%33%19%1
533
16th to endNight
14%5%26%35%15%1
621
September1st to 15thNight
22%427%24%18%2
720
16th to endNight
23%425%27%17%2
681
October1st to 15thNight
27%9%29%23%8%1
660
16th to endNight
36%11%24%19%6%
704
November1st to 15thNight
27%15%26%21%9%
700
16th to endNight
35%12%24%19%7%
720
December1st to 15thNight
32%14%30%15%5%
720
16th to endNight
35%14%28%17%31
867
Page generated at 2017-09-22 07:35:32. Version ac04

Copyright 2017 A. Danko


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