Nordegg
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Nordegg clear sky chart from 2005-11-06 to 2024-02-05.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	10% 10% 4 8% 7% 4 6% 6% 6% 8% 31%	78242
	Night	6% 10% 5% 9% 7% 4 5% 6% 6% 8% 35%	80563
Transparency	Day	50% 4 14% 21% 10% 1	77944
	Night	47% 3 15% 23% 11% 2	80441
Seeing	Day	18% 17% 30% 23% 10% 2	14710
	Night	14% 13% 32% 28% 12% 1	23354

By Month

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	2 6% 5% 13% 10% 5% 6% 5% 7% 8% 32%	2219
	11th to 20th	Day	3 8% 4 9% 8% 4 6% 8% 6% 9% 36%	2294
	21st to end	Day	3 9% 5% 7% 7% 3 6% 7% 7% 9% 38%	2794
February	1st to 10th	Day	4 9% 6% 10% 9% 5% 7% 6% 7% 7% 30%	1472
	11th to 20th	Day	3 12% 7% 12% 8% 4 6% 6% 6% 8% 28%	1475
	21st to end	Day	2 8% 6% 13% 10% 5% 7% 6% 6% 6% 30%	1480
March	1st to 10th	Day	2 8% 5% 12% 8% 6% 6% 5% 6% 10% 31%	1800
	11th to 20th	Day	2 8% 6% 10% 8% 4 7% 6% 8% 10% 32%	1883
	21st to end	Day	4 15% 8% 12% 9% 5% 5% 6% 5% 8% 24%	2305
April	1st to 10th	Day	6% 15% 6% 10% 9% 5% 7% 6% 7% 8% 21%	2160
	11th to 20th	Day	9% 18% 6% 10% 8% 4 5% 6% 6% 7% 22%	2308
	21st to end	Day	10% 15% 6% 11% 7% 4 6% 4 5% 6% 25%	2384
May	1st to 10th	Day	15% 16% 5% 10% 8% 4 6% 5% 5% 7% 20%	2521
	11th to 20th	Day	12% 9% 4 7% 7% 4 6% 4 6% 8% 32%	2654
	21st to end	Day	22% 11% 4 8% 7% 3 5% 5% 5% 6% 24%	2917
June	1st to 10th	Day	20% 9% 4 7% 6% 4 6% 5% 7% 7% 24%	2706
	11th to 20th	Day	23% 10% 4 7% 8% 4 6% 7% 5% 7% 19%	2880
	21st to end	Day	12% 7% 3 7% 8% 4 6% 6% 7% 8% 31%	2880
July	1st to 10th	Day	13% 8% 3 7% 6% 4 6% 7% 7% 8% 30%	2877
	11th to 20th	Day	14% 6% 3 6% 7% 3 6% 6% 7% 9% 34%	2700
	21st to end	Day	11% 6% 3 5% 5% 4 6% 6% 7% 9% 37%	2840
August	1st to 10th	Day	14% 8% 3 6% 6% 4 5% 5% 7% 8% 33%	2507
	11th to 20th	Day	12% 6% 2 7% 5% 3 6% 5% 7% 9% 38%	2435
	21st to end	Day	14% 7% 3 6% 6% 4 5% 6% 6% 8% 36%	2574
September	1st to 10th	Day	14% 11% 3 6% 6% 3 4 5% 5% 6% 37%	2174
	11th to 20th	Day	15% 8% 3 5% 6% 2 5% 5% 6% 8% 39%	2041
	21st to end	Day	11% 9% 3 7% 6% 4 4 5% 5% 8% 38%	1980
October	1st to 10th	Day	10% 11% 4 7% 5% 3 4 6% 5% 7% 36%	1897
	11th to 20th	Day	9% 10% 4 8% 5% 3 5% 4 5% 7% 39%	1620
	21st to end	Day	6% 13% 5% 9% 8% 3 5% 5% 5% 7% 32%	1782
November	1st to 10th	Day	5% 12% 7% 10% 8% 3 5% 5% 7% 7% 32%	1569
	11th to 20th	Day	4 10% 5% 8% 7% 4 6% 5% 6% 9% 37%	1330
	21st to end	Day	4 9% 6% 9% 7% 4 4 6% 7% 10% 34%	1330
December	1st to 10th	Day	4 10% 6% 13% 8% 3 7% 5% 6% 7% 32%	1330
	11th to 20th	Day	2 9% 5% 11% 9% 4 6% 6% 7% 7% 34%	1682
	21st to end	Day	2 10% 5% 9% 6% 3 5% 6% 5% 7% 42%	2442
January	1st to 10th	Night	1 9% 7% 14% 9% 4 6% 6% 7% 8% 30%	4726
	11th to 20th	Night	2 7% 4 10% 9% 5% 5% 6% 8% 8% 35%	4635
	21st to end	Night	3 11% 5% 9% 8% 5% 6% 5% 6% 9% 34%	4862
February	1st to 10th	Night	4 11% 5% 11% 11% 5% 6% 5% 5% 7% 31%	2582
	11th to 20th	Night	3 13% 6% 10% 9% 4 7% 6% 6% 8% 27%	2368
	21st to end	Night	2 7% 7% 12% 9% 5% 6% 6% 5% 6% 35%	1776
March	1st to 10th	Night	2 8% 5% 10% 8% 5% 7% 8% 7% 9% 31%	2160
	11th to 20th	Night	3 9% 5% 7% 6% 4 6% 7% 7% 8% 38%	2075
	21st to end	Night	3 13% 7% 11% 7% 4 5% 5% 6% 9% 31%	2048
April	1st to 10th	Night	5% 12% 6% 10% 7% 5% 6% 6% 6% 9% 29%	1800
	11th to 20th	Night	8% 14% 5% 9% 8% 4 4 5% 5% 7% 30%	1602
	21st to end	Night	8% 15% 4 8% 5% 3 6% 6% 6% 7% 32%	1575
May	1st to 10th	Night	13% 14% 4 9% 7% 5% 4 6% 5% 7% 26%	1437
	11th to 20th	Night	10% 9% 3 5% 7% 4 5% 6% 8% 7% 38%	1239
	21st to end	Night	20% 10% 3 4 5% 3 5% 5% 6% 8% 31%	1358
June	1st to 10th	Night	19% 8% 3 6% 5% 3 5% 5% 5% 8% 33%	1250
	11th to 20th	Night	21% 8% 3 6% 6% 3 5% 6% 7% 8% 27%	1080
	21st to end	Night	11% 6% 3 6% 6% 3 4 5% 8% 8% 39%	1080
July	1st to 10th	Night	13% 7% 3 6% 5% 3 5% 4 7% 8% 38%	1080
	11th to 20th	Night	12% 6% 3 5% 7% 3 5% 6% 7% 8% 38%	1260
	21st to end	Night	8% 4 3 4 5% 3 5% 6% 5% 9% 47%	1475
August	1st to 10th	Night	12% 6% 2 6% 5% 3 4 4 8% 9% 41%	1432
	11th to 20th	Night	11% 7% 2 5% 4 3 4 5% 6% 8% 46%	1464
	21st to end	Night	13% 7% 3 5% 5% 2 4 4 5% 9% 42%	1782
September	1st to 10th	Night	12% 8% 3 6% 5% 3 4 6% 5% 7% 42%	1784
	11th to 20th	Night	15% 9% 3 5% 4 3 3 4 5% 7% 40%	1918
	21st to end	Night	9% 9% 3 5% 4 3 4 6% 6% 7% 43%	1980
October	1st to 10th	Night	10% 11% 4 5% 5% 3 4 4 5% 8% 41%	2060
	11th to 20th	Night	9% 10% 3 7% 6% 4 4 5% 6% 6% 39%	2340
	21st to end	Night	5% 13% 5% 9% 6% 4 5% 5% 6% 7% 34%	2574
November	1st to 10th	Night	5% 14% 6% 11% 6% 3 5% 5% 5% 7% 34%	2487
	11th to 20th	Night	3 10% 5% 8% 6% 4 6% 6% 7% 9% 35%	2850
	21st to end	Night	4 9% 6% 11% 9% 4 5% 6% 6% 8% 33%	2850
December	1st to 10th	Night	4 11% 6% 9% 8% 4 6% 6% 5% 7% 34%	2850
	11th to 20th	Night	2 9% 6% 10% 9% 6% 7% 6% 7% 9% 29%	3510
	21st to end	Night	1 10% 6% 10% 7% 4 5% 5% 5% 8% 38%	5214

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	49% 2 11% 25% 10% 2	2219
	11th to 20th	Day	44% 2 12% 18% 20% 4	2315
	21st to end	Day	42% 3 19% 28% 8% 1	2794
February	1st to 10th	Day	51% 2 12% 19% 12% 4	1472
	11th to 20th	Day	54% 4 13% 18% 10% 1	1483
	21st to end	Day	53% 4 11% 16% 15% 1	1480
March	1st to 10th	Day	48% 4 16% 20% 11% 2	1800
	11th to 20th	Day	45% 4 13% 26% 11% 2	1884
	21st to end	Day	56% 4 14% 19% 6% 1	2305
April	1st to 10th	Day	60% 4 13% 16% 7% 1	2160
	11th to 20th	Day	61% 3 10% 18% 7% 1	2308
	21st to end	Day	60% 4 11% 18% 7% 1	2384
May	1st to 10th	Day	64% 3 11% 16% 6%	2521
	11th to 20th	Day	50% 3 15% 21% 10% 1	2658
	21st to end	Day	61% 4 12% 15% 8% 1	2918
June	1st to 10th	Day	57% 4 13% 19% 7% 1	2706
	11th to 20th	Day	62% 4 11% 15% 7% 1	2880
	21st to end	Day	48% 4 17% 21% 10% 1	2880
July	1st to 10th	Day	49% 5% 15% 21% 9% 1	2798
	11th to 20th	Day	45% 5% 16% 24% 9% 1	2619
	21st to end	Day	42% 4 17% 24% 11% 1	2682
August	1st to 10th	Day	47% 5% 15% 25% 7% 1	2490
	11th to 20th	Day	42% 3 19% 24% 10% 1	2435
	21st to end	Day	45% 4 13% 26% 9% 2	2574
September	1st to 10th	Day	48% 3 15% 23% 10% 2	2174
	11th to 20th	Day	45% 3 14% 26% 10% 2	2041
	21st to end	Day	45% 4 15% 21% 12% 3	1980
October	1st to 10th	Day	47% 4 13% 25% 10% 1	1897
	11th to 20th	Day	46% 3 16% 24% 10% 1	1620
	21st to end	Day	52% 4 12% 20% 11% 1	1782
November	1st to 10th	Day	51% 4 15% 19% 10% 2	1569
	11th to 20th	Day	45% 3 17% 21% 12% 1	1330
	21st to end	Day	43% 4 20% 21% 8% 3	1330
December	1st to 10th	Day	53% 4 13% 16% 12% 2	1330
	11th to 20th	Day	49% 3 15% 22% 10% 2	1684
	21st to end	Day	42% 2 10% 24% 17% 5%	2442
January	1st to 10th	Night	52% 2 11% 21% 11% 2	4726
	11th to 20th	Night	46% 3 13% 16% 17% 6%	4676
	21st to end	Night	48% 2 19% 22% 9% 1	4862
February	1st to 10th	Night	53% 3 11% 19% 11% 3	2582
	11th to 20th	Night	52% 4 14% 18% 11% 1	2370
	21st to end	Night	49% 2 10% 24% 13% 2	1776
March	1st to 10th	Night	47% 4 15% 22% 11% 1	2160
	11th to 20th	Night	42% 4 15% 24% 14% 1	2075
	21st to end	Night	50% 4 15% 21% 9% 1	2048
April	1st to 10th	Night	52% 4 13% 21% 10% 1	1800
	11th to 20th	Night	55% 2 13% 19% 10% 1	1602
	21st to end	Night	50% 4 13% 25% 7% 1	1575
May	1st to 10th	Night	57% 3 14% 20% 6%	1437
	11th to 20th	Night	43% 4 13% 26% 14%	1239
	21st to end	Night	51% 3 13% 25% 8% 1	1358
June	1st to 10th	Night	49% 4 16% 22% 9% 1	1250
	11th to 20th	Night	53% 4 17% 19% 6%	1080
	21st to end	Night	42% 4 18% 27% 8% 1	1080
July	1st to 10th	Night	42% 5% 17% 26% 9% 1	1050
	11th to 20th	Night	41% 5% 20% 24% 9%	1218
	21st to end	Night	33% 4 19% 31% 11% 1	1393
August	1st to 10th	Night	40% 3 21% 30% 6%	1424
	11th to 20th	Night	36% 4 22% 28% 9% 1	1464
	21st to end	Night	40% 3 16% 29% 11% 1	1782
September	1st to 10th	Night	41% 3 16% 28% 10% 2	1784
	11th to 20th	Night	44% 3 14% 26% 10% 3	1918
	21st to end	Night	39% 3 18% 26% 12% 2	1980
October	1st to 10th	Night	43% 3 15% 27% 10% 1	2060
	11th to 20th	Night	45% 3 17% 24% 11% 1	2340
	21st to end	Night	49% 5% 13% 23% 10%	2574
November	1st to 10th	Night	50% 3 12% 21% 12% 1	2487
	11th to 20th	Night	45% 4 17% 22% 11% 1	2850
	21st to end	Night	48% 4 15% 21% 10% 3	2850
December	1st to 10th	Night	49% 4 10% 22% 12% 3	2850
	11th to 20th	Night	51% 4 17% 20% 7% 1	3507
	21st to end	Night	45% 2 14% 23% 12% 4	5214

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	7% 17% 28% 32% 12% 4	180
	11th to 20th	Day	8% 14% 37% 28% 10% 3	180
	21st to end	Day	14% 19% 38% 21% 6% 2	198
February	1st to 10th	Day	17% 19% 36% 18% 6% 4	168
	11th to 20th	Day	9% 24% 37% 22% 8%	203
	21st to end	Day	9% 23% 32% 24% 10% 2	346
March	1st to 10th	Day	13% 24% 34% 18% 8% 3	420
	11th to 20th	Day	13% 21% 37% 19% 7% 4	420
	21st to end	Day	17% 25% 31% 18% 8% 2	462
April	1st to 10th	Day	22% 21% 30% 19% 6% 2	420
	11th to 20th	Day	21% 22% 25% 23% 8% 1	412
	21st to end	Day	20% 20% 29% 20% 8% 2	420
May	1st to 10th	Day	26% 18% 25% 23% 8%	424
	11th to 20th	Day	17% 12% 29% 25% 15% 2	625
	21st to end	Day	26% 11% 24% 24% 13% 3	679
June	1st to 10th	Day	22% 16% 29% 21% 10% 2	636
	11th to 20th	Day	27% 14% 26% 22% 9% 2	810
	21st to end	Day	16% 12% 28% 25% 16% 3	810
July	1st to 10th	Day	18% 10% 29% 28% 13% 3	793
	11th to 20th	Day	16% 11% 28% 26% 16% 2	618
	21st to end	Day	14% 12% 28% 30% 14% 3	586
August	1st to 10th	Day	16% 14% 26% 30% 10% 3	447
	11th to 20th	Day	14% 16% 30% 27% 9% 2	437
	21st to end	Day	18% 15% 30% 24% 11% 3	495
September	1st to 10th	Day	23% 20% 27% 21% 8% 1	450
	11th to 20th	Day	21% 17% 29% 22% 8% 3	450
	21st to end	Day	20% 22% 29% 19% 8% 2	450
October	1st to 10th	Day	20% 17% 29% 19% 12% 3	429
	11th to 20th	Day	17% 17% 34% 19% 11% 2	270
	21st to end	Day	22% 15% 34% 19% 8% 1	297
November	1st to 10th	Day	19% 26% 28% 19% 5% 2	257
	11th to 20th	Day	16% 23% 34% 21% 5% 1	180
	21st to end	Day	8% 31% 27% 23% 8% 3	180
December	1st to 10th	Day	12% 22% 32% 19% 11% 4	180
	11th to 20th	Day	10% 21% 38% 22% 8% 1	180
	21st to end	Day	7% 16% 38% 28% 11% 1	198
January	1st to 10th	Night	12% 16% 38% 27% 7% 1	950
	11th to 20th	Night	10% 17% 41% 24% 7% 1	912
	21st to end	Night	12% 20% 38% 22% 8% 1	836
February	1st to 10th	Night	13% 17% 31% 26% 11% 2	738
	11th to 20th	Night	13% 14% 39% 26% 9%	704
	21st to end	Night	5% 11% 37% 30% 14% 2	592
March	1st to 10th	Night	7% 16% 36% 28% 12% 2	720
	11th to 20th	Night	9% 14% 37% 28% 10% 2	720
	21st to end	Night	11% 13% 32% 30% 12% 3	792
April	1st to 10th	Night	13% 14% 28% 29% 14% 1	720
	11th to 20th	Night	18% 13% 31% 27% 10%	534
	21st to end	Night	21% 13% 27% 27% 11%	495
May	1st to 10th	Night	21% 8% 24% 30% 15% 1	360
	11th to 20th	Night	13% 8% 25% 38% 15% 1	354
	21st to end	Night	23% 4 23% 27% 21% 1	389
June	1st to 10th	Night	24% 8% 26% 24% 16% 2	360
	11th to 20th	Night	23% 6% 22% 31% 17% 2	360
	21st to end	Night	14% 6% 23% 31% 24% 3	360
July	1st to 10th	Night	16% 3 22% 37% 23%	350
	11th to 20th	Night	16% 5% 27% 30% 21%	348
	21st to end	Night	11% 6% 17% 38% 25% 3	394
August	1st to 10th	Night	18% 2 16% 31% 30% 4	358
	11th to 20th	Night	13% 6% 17% 37% 25% 2	396
	21st to end	Night	14% 8% 21% 36% 20% 1	594
September	1st to 10th	Night	17% 7% 25% 32% 17% 2	704
	11th to 20th	Night	21% 7% 21% 30% 18% 3	720
	21st to end	Night	15% 12% 30% 28% 13% 2	720
October	1st to 10th	Night	18% 9% 26% 33% 13% 1	720
	11th to 20th	Night	16% 13% 31% 30% 8% 2	720
	21st to end	Night	16% 13% 36% 27% 6% 2	792
November	1st to 10th	Night	15% 15% 36% 25% 8% 1	797
	11th to 20th	Night	12% 21% 41% 21% 5% 1	950
	21st to end	Night	11% 20% 37% 23% 8% 1	950
December	1st to 10th	Night	11% 17% 40% 21% 10% 1	950
	11th to 20th	Night	7% 18% 39% 26% 9% 1	950
	21st to end	Night	8% 15% 42% 24% 9% 1	1045

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