Niverville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Niverville clear sky chart from 2005-11-05 to 2017-10-06.

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
38%
16344
12%
47001
7%
16300
42%
16300
21%
33375

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
30%
900
8%
2685
6%
895
33%
895
13%
2104
January16th to endNight
27%
960
9%
2745
5%
960
31%
960
13%
2206
February1st to 15thNight
39%
876
10%
2330
6%
875
41%
875
18%
1767
February16th to endNight
37%
753
12%
2015
6%
753
40%
753
16%
1551
March1st to 15thNight
36%
629
13%
2069
9%
629
41%
629
18%
1458
March16th to endNight
39%
576
13%
2112
11%
576
46%
576
17%
1418
April1st to 15thNight
42%
539
17%
1717
16%
539
49%
539
25%
1095
April16th to endNight
40%
540
16%
1620
12%
540
44%
540
23%
1092
May1st to 15thNight
35%
540
12%
1499
4%
540
38%
540
24%
1042
May16th to endNight
40%
563
12%
1311
5%
561
43%
561
30%
917
June1st to 15thNight
45%
540
4%
1260
3%
540
46%
540
32%
865
June16th to endNight
51%
540
4%
1260
3%
540
53%
540
33%
858
July1st to 15thNight
61%
510
7%
1190
5%
510
63%
510
45%
735
July16th to endNight
62%
564
14%
1259
7%
531
63%
531
48%
745
August1st to 15thNight
59%
539
17%
1558
9%
536
63%
536
39%
883
August16th to endNight
58%
573
22%
1719
20%
573
64%
573
42%
935
September1st to 15thNight
54%
540
18%
1812
17%
540
59%
540
35%
986
September16th to endNight
44%
537
19%
1980
17%
537
50%
537
24%
1209
October1st to 15thNight
32%
651
14%
2019
9%
651
36%
651
19%
1403
October16th to endNight
33%
839
12%
2247
6%
839
37%
839
20%
1645
November1st to 15thNight
25%
875
11%
2434
3%
875
31%
875
17%
1826
November16th to endNight
24%
900
10%
2580
6%
900
28%
900
13%
2018
December1st to 15thNight
31%
900
6%
2700
5%
900
33%
900
11%
2191
December16th to endNight
22%
960
7%
2880
3%
960
25%
960
8%
2426

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
13%8%36%6%35%5%5%7%33%
48227
Night
12%9%47%6%35%5%5%6%33%
47148
Cloud CoverDay
13%8%37%6%35%5%5%7%33%
48237
Night
11%9%47%6%35%5%5%6%33%
47151
Cloud CoverDay
13%8%37%6%35%5%5%7%33%
48238
Night
12%9%47%6%35%5%5%6%33%
47152
Cloud CoverDay
13%8%47%6%35%5%5%7%33%
48236
Night
11%9%47%6%35%5%5%6%33%
47152
TransparencyDay
49%5%15%22%6%
47891
Night
49%5%14%21%7%
47001
SeeingDay
16%7%27%28%15%4
6328
Night
16%5%28%33%13%1
16348

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
8%13%6%8%9%5%7%7%7%6%20%
1253
16th to endDay
11%14%7%11%9%6%7%7%6%412%
1479
February1st to 15thDay
7%9%6%9%9%5%7%7%6%8%23%
1533
16th to endDay
10%10%411%8%6%7%7%6%7%18%
1468
March1st to 15thDay
12%11%6%9%10%36%5%35%24%
1879
16th to endDay
12%11%48%8%35%5%6%7%26%
2112
April1st to 15thDay
11%9%5%7%5%35%435%38%
2228
16th to endDay
15%8%36%5%3445%6%35%
2340
May1st to 15thDay
20%10%26%5%34446%32%
2450
16th to endDay
20%6%25%42445%7%35%
2803
June1st to 15thDay
17%6%36%5%26%5%5%8%31%
2700
16th to endDay
14%6%35%5%35%6%6%7%34%
2700
July1st to 15thDay
11%324435%5%6%8%43%
2700
16th to endDay
7%4145%345%6%9%48%
2822
August1st to 15thDay
10%424435%6%6%8%43%
2394
16th to endDay
11%41332345%8%50%
2483
September1st to 15thDay
10%5%26%424448%46%
2148
16th to endDay
16%5%25%42335%7%42%
1980
October1st to 15thDay
17%10%37%5%2445%6%32%
1727
16th to endDay
18%11%37%5%25%45%7%27%
1623
November1st to 15thDay
14%13%5%7%5%24447%29%
1424
16th to endDay
14%15%6%9%7%45%35%5%22%
1377
December1st to 15thDay
9%17%7%11%9%47%5%5%6%14%
1260
16th to endDay
14%16%8%11%9%34445%15%
1344
January1st to 15thNight
8%14%6%10%9%46%6%6%6%19%
2685
16th to endNight
10%13%6%11%7%36%7%6%6%18%
2745
February1st to 15thNight
8%9%49%7%48%7%5%5%27%
2327
16th to endNight
8%11%6%10%8%46%5%45%26%
2015
March1st to 15thNight
11%11%5%8%7%34446%32%
2057
16th to endNight
14%9%46%5%245%6%7%33%
2112
April1st to 15thNight
11%7%25%5%35%46%6%40%
1717
16th to endNight
14%7%36%5%35%5%45%38%
1620
May1st to 15thNight
17%9%35%434347%36%
1499
16th to endNight
16%5%244245%5%7%41%
1310
June1st to 15thNight
14%4244345%6%7%42%
1260
16th to endNight
11%435%43446%8%42%
1260
July1st to 15thNight
6%21332436%8%55%
1260
16th to endNight
5%2134335%6%8%55%
1344
August1st to 15thNight
8%31432446%7%52%
1566
16th to endNight
8%214322347%57%
1719
September1st to 15thNight
8%4133245%47%53%
1812
16th to endNight
15%5%24425%447%42%
1980
October1st to 15thNight
16%10%36%5%35%45%7%32%
2019
16th to endNight
16%10%27%5%3445%6%32%
2247
November1st to 15thNight
14%13%6%7%5%24445%30%
2434
16th to endNight
13%12%6%10%8%34446%23%
2580
December1st to 15thNight
9%14%6%11%9%6%5%5%6%6%17%
2700
16th to endNight
14%15%8%12%10%5%5%43414%
2880

Percentage Cloud Cover NW (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
8%13%6%8%8%6%6%7%7%5%21%
1254
16th to endDay
12%14%6%11%10%6%8%6%6%412%
1479
February1st to 15thDay
7%9%6%9%8%5%9%6%6%8%22%
1533
16th to endDay
10%10%5%12%8%6%6%7%7%6%18%
1468
March1st to 15thDay
12%11%7%9%9%45%6%45%24%
1890
16th to endDay
12%11%47%9%46%5%5%8%25%
2110
April1st to 15thDay
11%9%5%6%5%35%346%37%
2228
16th to endDay
16%8%37%5%3445%7%34%
2340
May1st to 15thDay
20%9%36%5%34445%32%
2450
16th to endDay
20%6%25%43445%6%36%
2803
June1st to 15thDay
17%7%26%5%35%5%5%8%31%
2700
16th to endDay
14%6%36%5%36%6%6%7%35%
2700
July1st to 15thDay
10%3245%35%5%6%8%43%
2700
16th to endDay
7%4244345%6%8%48%
2822
August1st to 15thDay
10%424435%5%7%8%42%
2394
16th to endDay
11%42332345%7%51%
2483
September1st to 15thDay
10%6%25%5%2435%8%46%
2148
16th to endDay
16%5%2442345%8%42%
1980
October1st to 15thDay
16%10%37%5%34446%32%
1727
16th to endDay
17%11%38%5%25%5%5%6%28%
1623
November1st to 15thDay
14%13%5%8%5%345%46%29%
1424
16th to endDay
14%15%5%9%8%35%345%23%
1377
December1st to 15thDay
9%16%7%10%10%47%5%5%6%14%
1260
16th to endDay
13%17%8%11%11%34345%16%
1344
January1st to 15thNight
8%14%7%10%9%46%7%6%6%19%
2685
16th to endNight
10%13%7%10%8%46%7%6%6%18%
2745
February1st to 15thNight
8%9%49%7%49%7%5%6%26%
2320
16th to endNight
8%11%5%10%9%46%6%5%5%26%
2015
March1st to 15thNight
11%10%5%8%7%35%446%32%
2069
16th to endNight
14%9%46%5%25%46%6%33%
2110
April1st to 15thNight
10%7%35%5%35%5%6%7%39%
1717
16th to endNight
13%7%46%5%345%45%38%
1620
May1st to 15thNight
17%8%45%5%24347%36%
1498
16th to endNight
16%5%334335%5%7%40%
1311
June1st to 15thNight
14%5%144245%5%8%42%
1260
16th to endNight
10%5%25%6%3436%9%42%
1260
July1st to 15thNight
6%31332446%8%54%
1260
16th to endNight
43134235%6%8%55%
1344
August1st to 15thNight
8%31333445%7%52%
1566
16th to endNight
8%31432335%8%57%
1719
September1st to 15thNight
8%41342345%6%53%
1812
16th to endNight
15%5%245%25%347%43%
1980
October1st to 15thNight
16%9%36%5%35%45%7%32%
2019
16th to endNight
16%9%36%6%3445%6%32%
2247
November1st to 15thNight
14%14%5%8%434335%31%
2434
16th to endNight
13%12%6%10%8%44446%24%
2580
December1st to 15thNight
9%15%7%10%10%5%6%5%6%6%17%
2700
16th to endNight
13%15%8%12%10%5%5%43414%
2880

Percentage Cloud Cover SW (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
8%13%6%7%9%6%6%7%7%6%20%
1253
16th to endDay
11%15%6%10%10%6%7%7%6%5%12%
1479
February1st to 15thDay
6%9%6%9%9%5%8%7%6%7%23%
1533
16th to endDay
10%10%5%11%8%5%7%7%6%6%19%
1468
March1st to 15thDay
13%11%6%9%10%36%5%36%23%
1890
16th to endDay
12%11%47%9%36%46%7%26%
2112
April1st to 15thDay
11%9%47%5%25%436%38%
2228
16th to endDay
15%8%36%5%3445%6%35%
2340
May1st to 15thDay
20%10%35%5%34445%32%
2450
16th to endDay
20%6%35%42445%7%35%
2803
June1st to 15thDay
17%6%36%5%35%45%8%31%
2700
16th to endDay
15%5%35%5%35%6%6%7%34%
2700
July1st to 15thDay
10%315%425%5%6%9%43%
2700
16th to endDay
7%4144345%6%8%48%
2822
August1st to 15thDay
10%425%435%5%7%8%42%
2394
16th to endDay
11%413323448%50%
2483
September1st to 15thDay
10%5%25%423348%46%
2148
16th to endDay
17%5%2441345%7%42%
1980
October1st to 15thDay
17%10%37%5%2445%6%32%
1727
16th to endDay
18%11%37%5%25%45%7%27%
1623
November1st to 15thDay
14%14%5%7%5%33447%29%
1424
16th to endDay
14%15%6%9%7%45%345%22%
1377
December1st to 15thDay
9%17%7%11%9%46%6%6%5%15%
1260
16th to endDay
14%16%8%12%9%34445%15%
1344
January1st to 15thNight
8%14%6%10%8%46%7%6%6%18%
2685
16th to endNight
11%13%6%11%7%46%7%6%6%18%
2745
February1st to 15thNight
8%9%49%7%5%8%8%45%27%
2320
16th to endNight
8%11%5%10%8%5%6%5%45%26%
2015
March1st to 15thNight
11%11%48%7%34446%32%
2069
16th to endNight
14%9%46%5%245%6%6%34%
2112
April1st to 15thNight
11%7%25%5%35%36%7%40%
1717
16th to endNight
13%8%35%6%35%445%37%
1620
May1st to 15thNight
17%10%35%424347%37%
1498
16th to endNight
16%5%3441445%7%41%
1310
June1st to 15thNight
14%4244345%6%7%42%
1260
16th to endNight
11%425%4345%6%8%42%
1260
July1st to 15thNight
6%21433336%8%56%
1260
16th to endNight
5%333245%6%9%55%
1344
August1st to 15thNight
8%31432446%7%52%
1566
16th to endNight
8%314323447%58%
1719
September1st to 15thNight
8%413424447%52%
1812
16th to endNight
15%5%24424447%42%
1980
October1st to 15thNight
16%10%35%5%35%46%6%32%
2019
16th to endNight
16%10%37%5%3445%6%32%
2247
November1st to 15thNight
14%13%5%7%5%24445%30%
2434
16th to endNight
13%12%6%10%8%44447%23%
2580
December1st to 15thNight
9%14%6%10%10%5%5%6%6%6%17%
2700
16th to endNight
14%15%8%12%10%5%5%435%14%
2880

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
8%13%5%8%9%5%7%6%7%6%20%
1253
16th to endDay
11%15%7%10%10%6%7%7%6%5%11%
1479
February1st to 15thDay
7%9%5%9%9%5%8%7%6%7%23%
1533
16th to endDay
10%10%6%11%8%6%7%7%6%6%19%
1468
March1st to 15thDay
12%11%6%9%10%46%5%46%23%
1890
16th to endDay
12%11%38%8%36%5%6%7%25%
2110
April1st to 15thDay
10%9%47%5%25%446%37%
2228
16th to endDay
15%8%36%5%3445%6%35%
2340
May1st to 15thDay
20%10%35%434446%31%
2450
16th to endDay
20%6%35%42445%7%34%
2803
June1st to 15thDay
17%7%36%6%36%46%8%30%
2700
16th to endDay
14%5%46%5%35%6%6%7%34%
2700
July1st to 15thDay
10%3245%25%6%6%9%42%
2700
16th to endDay
6%4244345%6%8%47%
2822
August1st to 15thDay
10%424435%5%6%8%42%
2394
16th to endDay
11%5%13323448%50%
2483
September1st to 15thDay
10%6%26%42435%8%45%
2148
16th to endDay
16%6%25%42345%7%42%
1980
October1st to 15thDay
16%10%37%6%2445%5%32%
1727
16th to endDay
17%10%47%6%25%45%8%26%
1623
November1st to 15thDay
14%14%6%7%5%33437%29%
1424
16th to endDay
14%14%6%10%8%45%435%21%
1377
December1st to 15thDay
8%18%7%11%10%46%7%5%5%15%
1260
16th to endDay
13%17%8%12%9%345%45%15%
1344
January1st to 15thNight
8%14%6%11%8%5%6%6%6%6%18%
2685
16th to endNight
10%14%6%11%7%46%7%6%6%17%
2745
February1st to 15thNight
8%10%49%6%5%8%8%5%5%26%
2320
16th to endNight
8%11%5%10%9%46%5%45%26%
2015
March1st to 15thNight
11%11%5%8%7%34446%32%
2069
16th to endNight
14%9%47%5%245%5%7%33%
2112
April1st to 15thNight
11%7%35%6%35%36%7%39%
1717
16th to endNight
13%8%35%6%35%45%5%37%
1620
May1st to 15thNight
17%9%35%424347%37%
1498
16th to endNight
16%5%35%424447%41%
1310
June1st to 15thNight
14%4244345%5%8%41%
1260
16th to endNight
10%5%35%4345%6%7%42%
1260
July1st to 15thNight
6%31433346%8%55%
1260
16th to endNight
5%2134245%6%9%54%
1344
August1st to 15thNight
8%31442446%6%52%
1566
16th to endNight
8%314323347%57%
1719
September1st to 15thNight
8%423333447%52%
1812
16th to endNight
15%5%344245%47%42%
1980
October1st to 15thNight
16%11%36%435%46%6%32%
2019
16th to endNight
16%10%37%6%3445%6%32%
2247
November1st to 15thNight
14%13%6%8%5%34345%29%
2434
16th to endNight
12%12%6%10%8%45%35%6%23%
2580
December1st to 15thNight
9%14%6%10%10%5%6%5%7%6%16%
2700
16th to endNight
14%16%7%12%10%5%5%445%13%
2880

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
58%6%14%15%4
1254
16th to endDay
70%5%8%13%2
1479
February1st to 15thDay
57%5%14%16%6%
1534
16th to endDay
61%5%12%15%4
1468
March1st to 15thDay
61%7%12%14%4
1890
16th to endDay
55%7%14%16%5%
2112
April1st to 15thDay
47%412%26%7%1
2228
16th to endDay
47%414%21%9%2
2340
May1st to 15thDay
53%49%24%7%
2450
16th to endDay
47%5%11%23%10%1
2807
June1st to 15thDay
49%5%14%21%7%
2700
16th to endDay
45%7%19%21%5%
2700
July1st to 15thDay
34%6%18%31%8%
2541
16th to endDay
32%6%20%29%9%
2644
August1st to 15thDay
35%8%19%28%7%
2378
16th to endDay
31%5%18%35%9%
2483
September1st to 15thDay
36%5%19%29%8%
2148
16th to endDay
40%5%19%29%5%
1980
October1st to 15thDay
51%5%15%21%6%
1727
16th to endDay
54%7%18%15%3
1623
November1st to 15thDay
54%5%17%16%41
1424
16th to endDay
64%414%13%3
1377
December1st to 15thDay
67%6%15%9%1
1260
16th to endDay
70%410%11%3
1344
January1st to 15thNight
61%5%11%16%4
2685
16th to endNight
62%6%11%15%3
2745
February1st to 15thNight
54%6%16%15%6%
2330
16th to endNight
57%5%12%18%5%
2015
March1st to 15thNight
52%413%21%7%
2069
16th to endNight
48%6%15%21%7%
2112
April1st to 15thNight
42%411%22%16%2
1717
16th to endNight
47%310%24%11%1
1620
May1st to 15thNight
47%412%23%11%
1499
16th to endNight
41%6%11%22%15%2
1311
June1st to 15thNight
39%6%15%26%10%1
1260
16th to endNight
37%7%23%23%7%1
1260
July1st to 15thNight
25%7%17%34%13%1
1190
16th to endNight
24%5%19%35%13%1
1259
August1st to 15thNight
28%5%18%35%9%1
1558
16th to endNight
26%417%34%15%1
1719
September1st to 15thNight
29%5%17%34%11%1
1812
16th to endNight
40%5%16%27%10%
1980
October1st to 15thNight
49%5%16%21%6%
2019
16th to endNight
51%5%16%23%2
2247
November1st to 15thNight
56%415%16%5%1
2434
16th to endNight
60%5%14%14%4
2580
December1st to 15thNight
64%7%14%12%1
2700
16th to endNight
72%410%10%2
2880

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
8%10%22%36%17%4
90
16th to endDay
23%5%18%35%15%1
96
February1st to 15thDay
12%11%42%27%6%
90
16th to endDay
23%137%30%7%
81
March1st to 15thDay
12%11%28%36%11%
90
16th to endDay
21%9%33%17%12%5%
96
April1st to 15thDay
14%10%31%29%12%
347
16th to endDay
18%7%28%31%11%2
450
May1st to 15thDay
23%11%30%22%11%1
468
16th to endDay
22%9%25%25%13%3
517
June1st to 15thDay
19%8%27%26%11%6%
495
16th to endDay
14%8%26%31%14%5%
495
July1st to 15thDay
14%424%28%20%7%
475
16th to endDay
8%6%26%29%21%7%
515
August1st to 15thDay
9%425%29%20%9%
493
16th to endDay
10%6%26%29%21%5%
523
September1st to 15thDay
10%5%30%34%16%1
303
16th to endDay
22%8%37%17%9%3
135
October1st to 15thDay
22%11%23%32%9%
107
16th to endDay
27%7%23%31%9%1
96
November1st to 15thDay
22%12%17%33%14%
90
16th to endDay
38%8%23%17%10%1
90
December1st to 15thDay
16%122%41%16%2
90
16th to endDay
17%7%26%32%10%6%
96
January1st to 15thNight
14%7%31%30%14%1
900
16th to endNight
17%8%33%32%8%
960
February1st to 15thNight
13%6%25%34%17%2
880
16th to endNight
13%5%28%33%16%3
753
March1st to 15thNight
16%6%30%30%14%2
629
16th to endNight
18%5%28%27%16%3
576
April1st to 15thNight
13%7%29%37%10%
539
16th to endNight
17%5%28%37%11%
540
May1st to 15thNight
21%6%28%33%9%
540
16th to endNight
17%5%30%33%11%
563
June1st to 15thNight
16%5%27%34%15%
540
16th to endNight
12%423%39%17%1
540
July1st to 15thNight
8%321%43%21%
510
16th to endNight
6%222%43%20%3
564
August1st to 15thNight
9%122%42%19%4
539
16th to endNight
8%423%38%21%1
573
September1st to 15thNight
11%226%37%19%2
540
16th to endNight
17%428%35%13%
537
October1st to 15thNight
23%7%30%29%8%
651
16th to endNight
21%6%30%30%10%1
839
November1st to 15thNight
20%9%33%23%10%1
875
16th to endNight
19%6%36%28%7%1
900
December1st to 15thNight
16%428%36%13%1
900
16th to endNight
20%7%28%27%12%3
960
Page generated at 2017-10-07 13:07:52. Version ac04

Copyright 2017 A. Danko


Niverville Clear Sky Chart | Charts Home