Mills Norrie State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mills Norrie State Park clear sky chart from 2005-11-05 to

2017-09-12
.

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
35%
14912
18%
46794
10%
14881
44%
14881
22%
30843

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
25%
720
19%
2506
8%
716
40%
716
18%
1631
January16th to endNight
24%
768
19%
2625
8%
768
39%
768
18%
1701
February1st to 15thNight
21%
704
14%
2237
4%
701
34%
701
17%
1547
February16th to endNight
22%
631
22%
1893
9%
631
37%
631
20%
1263
March1st to 15thNight
25%
720
17%
2160
8%
720
36%
720
19%
1482
March16th to endNight
26%
768
22%
1990
8%
768
36%
768
23%
1366
April1st to 15thNight
22%
718
16%
1796
4%
718
28%
718
21%
1313
April16th to endNight
30%
684
17%
1764
4%
684
38%
684
25%
1219
May1st to 15thNight
28%
480
18%
1560
9%
480
37%
480
19%
1041
May16th to endNight
44%
374
14%
1497
14%
374
50%
374
19%
940
June1st to 15thNight
46%
360
13%
1440
12%
360
54%
360
18%
935
June16th to endNight
58%
360
14%
1440
18%
360
64%
360
27%
818
July1st to 15thNight
58%
340
13%
1360
19%
340
60%
340
22%
803
July16th to endNight
59%
376
16%
1418
20%
354
63%
354
24%
827
August1st to 15thNight
60%
509
18%
1580
14%
507
63%
507
30%
978
August16th to endNight
61%
764
19%
1910
12%
764
62%
764
33%
1271
September1st to 15thNight
48%
707
22%
1768
12%
707
52%
707
33%
1164
September16th to endNight
53%
657
26%
1809
18%
657
58%
657
35%
1108
October1st to 15thNight
42%
660
22%
1930
16%
660
49%
660
25%
1257
October16th to endNight
30%
704
16%
2214
8%
704
41%
704
21%
1503
November1st to 15thNight
33%
700
20%
2277
11%
700
47%
700
23%
1468
November16th to endNight
32%
720
18%
2412
12%
720
42%
720
19%
1598
December1st to 15thNight
27%
720
15%
2520
7%
720
38%
720
16%
1735
December16th to endNight
21%
768
15%
2688
5%
768
33%
768
16%
1875

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
15%6%25%5%3445%7%38%
47872
Night
16%6%25%42445%6%40%
46964
Cloud CoverDay
15%6%25%5%35%45%7%38%
47881
Night
16%6%25%42445%6%40%
46970
TransparencyDay
43%6%12%21%13%1
47560
Night
43%6%11%21%14%1
46794
SeeingDay
19%9%26%25%13%4
5720
Night
19%9%29%29%10%
14913

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
14%6%246%45%6%6%6%35%
1432
16th to endDay
12%7%45%5%35%5%5%8%37%
1597
February1st to 15thDay
14%9%37%6%35%45%6%32%
1622
16th to endDay
14%7%346%35%45%6%37%
1580
March1st to 15thDay
16%7%37%5%2445%6%35%
1790
16th to endDay
16%8%36%423346%40%
2232
April1st to 15thDay
18%8%35%5%24345%38%
2152
16th to endDay
15%6%245%24446%43%
2196
May1st to 15thDay
20%6%35%5%24446%34%
2401
16th to endDay
15%5%25%435%6%5%8%37%
2618
June1st to 15thDay
20%5%24435%46%8%33%
2520
16th to endDay
12%5%25%6%45%5%6%10%35%
2520
July1st to 15thDay
10%5%25%5%46%6%6%8%37%
2520
16th to endDay
10%425%5%36%6%7%10%37%
2654
August1st to 15thDay
12%5%25%5%35%6%7%9%38%
2355
16th to endDay
11%414425%5%6%8%43%
2292
September1st to 15thDay
14%5%24435%446%43%
2112
16th to endDay
13%5%1431345%5%49%
1821
October1st to 15thDay
18%6%25%423446%40%
1698
16th to endDay
18%6%25%5%35%446%36%
1658
November1st to 15thDay
16%6%24423337%43%
1581
16th to endDay
18%7%24324346%41%
1545
December1st to 15thDay
18%9%345%35%45%6%34%
1440
16th to endDay
20%7%37%434446%32%
1536
January1st to 15thNight
16%7%36%5%2435%6%38%
2506
16th to endNight
13%9%34435%45%6%38%
2625
February1st to 15thNight
13%8%46%5%36%445%35%
2236
16th to endNight
14%7%35%5%2445%5%39%
1893
March1st to 15thNight
18%8%24424447%37%
2147
16th to endNight
16%6%444245%4442%
1990
April1st to 15thNight
18%8%35%6%23347%34%
1796
16th to endNight
18%6%25%423436%42%
1764
May1st to 15thNight
19%8%25%424345%38%
1560
16th to endNight
15%5%24435%5%6%8%38%
1495
June1st to 15thNight
20%5%1433445%8%38%
1440
16th to endNight
12%4133235%7%10%44%
1440
July1st to 15thNight
12%425%4246%7%7%42%
1440
16th to endNight
10%5%25%4345%6%9%42%
1514
August1st to 15thNight
10%42443446%10%44%
1590
16th to endNight
13%42442446%8%44%
1910
September1st to 15thNight
14%5%25%324345%48%
1768
16th to endNight
12%424324346%51%
1809
October1st to 15thNight
18%5%245%24335%44%
1930
16th to endNight
20%7%25%5%23445%39%
2214
November1st to 15thNight
17%6%35%41335%5%42%
2277
16th to endNight
18%7%3443445%6%37%
2412
December1st to 15thNight
21%7%36%433446%34%
2520
16th to endNight
20%8%36%42445%7%32%
2688

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
14%6%246%45%6%6%5%36%
1432
16th to endDay
12%7%35%5%345%5%8%38%
1597
February1st to 15thDay
14%8%38%5%345%5%6%32%
1622
16th to endDay
15%7%35%5%35%347%37%
1580
March1st to 15thDay
17%8%36%5%34446%34%
1800
16th to endDay
16%8%35%5%23336%41%
2231
April1st to 15thDay
18%9%35%5%24345%38%
2152
16th to endDay
15%6%245%24445%44%
2196
May1st to 15thDay
20%6%35%5%25%35%6%34%
2401
16th to endDay
15%5%25%5%35%5%6%7%37%
2618
June1st to 15thDay
20%5%24435%5%5%9%34%
2520
16th to endDay
12%5%25%6%35%5%6%9%35%
2520
July1st to 15thDay
10%5%25%5%46%6%6%9%37%
2520
16th to endDay
10%425%5%36%6%7%9%38%
2654
August1st to 15thDay
12%5%245%25%6%7%9%38%
2355
16th to endDay
11%414435%5%6%8%44%
2292
September1st to 15thDay
14%5%244345%46%44%
2112
16th to endDay
13%5%1431445%6%49%
1821
October1st to 15thDay
19%6%25%33335%6%40%
1698
16th to endDay
18%6%26%5%35%35%6%36%
1658
November1st to 15thDay
17%5%24424346%43%
1581
16th to endDay
18%7%2442435%6%41%
1545
December1st to 15thDay
18%9%35%44445%6%34%
1440
16th to endDay
20%7%46%5%25%446%32%
1536
January1st to 15thNight
16%7%36%5%33446%38%
2506
16th to endNight
13%9%44425%5%5%6%38%
2625
February1st to 15thNight
13%8%47%5%36%45%436%
2229
16th to endNight
14%8%35%5%34446%40%
1893
March1st to 15thNight
18%7%345%35%446%37%
2160
16th to endNight
16%7%445%24445%41%
1990
April1st to 15thNight
19%7%35%6%3345%6%34%
1796
16th to endNight
18%6%25%423345%42%
1764
May1st to 15thNight
20%6%35%5%24445%39%
1560
16th to endNight
15%5%24435%5%6%8%38%
1495
June1st to 15thNight
20%5%14325%35%7%38%
1440
16th to endNight
12%3233245%7%10%44%
1440
July1st to 15thNight
12%415%425%6%6%8%42%
1440
16th to endNight
10%4345%345%7%9%41%
1514
August1st to 15thNight
10%4245%3446%9%44%
1590
16th to endNight
14%4245%2446%7%44%
1910
September1st to 15thNight
14%5%25%424336%48%
1768
16th to endNight
13%413324346%51%
1809
October1st to 15thNight
19%4145%23335%44%
1930
16th to endNight
20%7%25%423346%38%
2214
November1st to 15thNight
17%7%35%323346%42%
2277
16th to endNight
18%7%25%42445%6%37%
2412
December1st to 15thNight
21%7%35%5%34346%34%
2520
16th to endNight
20%9%36%42435%6%32%
2688

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
44%7%13%22%10%1
1433
16th to endDay
43%6%13%23%12%1
1597
February1st to 15thDay
50%7%11%17%12%1
1625
16th to endDay
46%411%22%13%1
1580
March1st to 15thDay
49%5%13%20%9%1
1800
16th to endDay
45%49%18%17%3
2232
April1st to 15thDay
47%49%21%13%3
2152
16th to endDay
42%5%8%22%18%3
2196
May1st to 15thDay
50%5%8%19%13%2
2401
16th to endDay
43%8%13%19%12%1
2622
June1st to 15thDay
47%7%14%19%10%1
2520
16th to endDay
42%8%13%22%11%1
2520
July1st to 15thDay
42%8%13%19%14%1
2371
16th to endDay
38%8%16%20%13%1
2487
August1st to 15thDay
38%10%14%22%13%
2341
16th to endDay
34%8%13%25%17%
2292
September1st to 15thDay
39%6%11%21%18%1
2112
16th to endDay
34%5%10%23%23%1
1821
October1st to 15thDay
43%5%11%23%14%2
1698
16th to endDay
47%5%11%21%12%1
1658
November1st to 15thDay
41%5%13%20%15%2
1581
16th to endDay
43%411%25%12%2
1545
December1st to 15thDay
49%6%14%19%7%1
1440
16th to endDay
51%6%14%17%9%
1536
January1st to 15thNight
45%5%13%20%12%2
2506
16th to endNight
44%6%11%23%12%2
2625
February1st to 15thNight
48%6%13%18%11%1
2237
16th to endNight
43%6%10%20%16%2
1893
March1st to 15thNight
46%6%11%20%12%2
2160
16th to endNight
43%49%20%17%3
1990
April1st to 15thNight
49%5%8%20%14%1
1796
16th to endNight
43%6%8%20%19%2
1764
May1st to 15thNight
46%5%10%18%16%2
1560
16th to endNight
41%8%15%20%13%1
1497
June1st to 15thNight
44%7%13%20%11%1
1440
16th to endNight
32%8%15%29%12%1
1440
July1st to 15thNight
36%9%12%25%14%1
1360
16th to endNight
35%8%14%24%13%3
1418
August1st to 15thNight
33%8%14%25%16%1
1580
16th to endNight
36%7%11%25%18%
1910
September1st to 15thNight
38%5%11%26%18%1
1768
16th to endNight
33%5%8%24%26%
1809
October1st to 15thNight
42%5%10%22%17%2
1930
16th to endNight
46%5%12%22%12%
2214
November1st to 15thNight
43%5%11%20%16%3
2277
16th to endNight
45%5%13%22%10%1
2412
December1st to 15thNight
50%5%13%19%10%
2520
16th to endNight
50%6%13%18%10%
2688

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
16%18%35%23%6%
60
16th to endDay
21%14%45%16%2
75
February1st to 15thDay
21%21%34%21%1
138
16th to endDay
20%15%34%25%4
239
March1st to 15thDay
24%17%26%27%4
270
16th to endDay
20%14%32%22%7%2
288
April1st to 15thDay
24%12%31%19%10%1
270
16th to endDay
20%11%30%22%8%6%
270
May1st to 15thDay
31%11%22%20%10%2
288
16th to endDay
19%8%25%28%14%4
331
June1st to 15thDay
25%8%24%26%14%1
315
16th to endDay
13%9%31%25%17%2
315
July1st to 15thDay
15%228%32%17%4
305
16th to endDay
11%223%33%21%7%
326
August1st to 15thDay
13%5%17%32%18%10%
313
16th to endDay
11%317%27%27%12%
332
September1st to 15thDay
15%10%20%23%18%11%
299
16th to endDay
15%424%20%17%16%
254
October1st to 15thDay
23%5%17%27%20%5%
255
16th to endDay
18%12%31%27%9%
253
November1st to 15thDay
22%6%24%30%13%2
235
16th to endDay
20%9%33%23%9%3
165
December1st to 15thDay
18%25%25%20%11%
60
16th to endDay
28%20%37%14%
64
January1st to 15thNight
19%12%35%28%4
720
16th to endNight
18%13%36%28%2
768
February1st to 15thNight
18%13%39%27%1
704
16th to endNight
19%14%38%24%3
631
March1st to 15thNight
23%15%33%25%3
720
16th to endNight
19%16%35%19%8%
768
April1st to 15thNight
24%11%36%22%3
718
16th to endNight
21%13%30%25%8%
684
May1st to 15thNight
22%8%35%26%7%
480
16th to endNight
18%326%38%13%
375
June1st to 15thNight
20%322%37%14%1
360
16th to endNight
14%21%45%16%
360
July1st to 15thNight
14%119%45%20%
340
16th to endNight
11%318%39%23%2
376
August1st to 15thNight
13%17%43%22%2
509
16th to endNight
15%113%37%26%4
764
September1st to 15thNight
18%223%35%18%1
707
16th to endNight
15%323%30%22%4
657
October1st to 15thNight
21%5%22%33%14%1
660
16th to endNight
24%9%30%29%5%
704
November1st to 15thNight
20%8%32%28%9%1
700
16th to endNight
23%10%29%26%9%1
720
December1st to 15thNight
23%11%32%25%6%
720
16th to endNight
25%10%37%22%2
768
Page generated at 2017-09-13 07:39:13. Version ac04

Copyright 2017 A. Danko


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