Pigeon Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pigeon Lake clear sky chart from 2005-11-06 to 2024-12-02.

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% 9% 3 8% 5% 5% 5% 4 6% 8% 35%	106317
	Night	9% 10% 4 9% 6% 5% 5% 4 6% 8% 33%	101879
Transparency	Day	45% 5% 17% 23% 9% 1	106060
	Night	48% 5% 15% 21% 9% 1	101782
Seeing	Day	14% 6% 24% 30% 19% 7%	15812
	Night	14% 6% 29% 34% 15% 2	24490

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	4 12% 5% 13% 8% 5% 5% 5% 6% 7% 31%	2219
	11th to 20th	Day	5% 10% 4 9% 6% 5% 5% 7% 7% 9% 32%	2199
	21st to end	Day	6% 12% 5% 10% 5% 5% 6% 4 6% 6% 35%	2698
February	1st to 10th	Day	9% 14% 4 12% 7% 5% 6% 4 8% 7% 25%	1520
	11th to 20th	Day	4 14% 5% 13% 6% 6% 5% 4 7% 6% 29%	1596
	21st to end	Day	2 13% 5% 13% 8% 8% 7% 5% 5% 8% 24%	1498
March	1st to 10th	Day	3 12% 5% 15% 9% 7% 6% 4 4 6% 29%	3138
	11th to 20th	Day	5% 10% 3 7% 4 3 4 4 6% 10% 43%	3422
	21st to end	Day	6% 18% 6% 14% 5% 5% 4 4 6% 7% 24%	3917
April	1st to 10th	Day	8% 14% 4 9% 7% 5% 5% 5% 7% 8% 28%	2348
	11th to 20th	Day	11% 14% 4 9% 5% 5% 5% 5% 7% 8% 27%	2440
	21st to end	Day	12% 10% 3 9% 6% 5% 5% 5% 6% 8% 30%	2470
May	1st to 10th	Day	16% 11% 3 8% 5% 5% 5% 4 6% 6% 30%	4593
	11th to 20th	Day	12% 11% 3 9% 6% 5% 6% 4 6% 8% 29%	4694
	21st to end	Day	14% 8% 3 9% 5% 6% 6% 5% 7% 9% 27%	5161
June	1st to 10th	Day	16% 8% 3 6% 5% 5% 5% 4 7% 9% 31%	2850
	11th to 20th	Day	18% 10% 3 8% 6% 6% 6% 5% 6% 6% 25%	2927
	21st to end	Day	10% 5% 2 6% 5% 5% 5% 5% 8% 9% 39%	3040
July	1st to 10th	Day	10% 6% 2 5% 4 3 4 3 6% 9% 50%	4844
	11th to 20th	Day	9% 4 2 5% 5% 4 4 4 6% 8% 49%	4740
	21st to end	Day	12% 5% 2 5% 4 4 5% 5% 6% 9% 44%	5138
August	1st to 10th	Day	12% 6% 2 7% 4 5% 5% 4 6% 8% 41%	4436
	11th to 20th	Day	9% 6% 2 6% 5% 5% 5% 4 7% 10% 42%	4176
	21st to end	Day	11% 6% 2 6% 5% 5% 5% 4 7% 9% 41%	4521
September	1st to 10th	Day	13% 5% 2 6% 4 5% 4 4 6% 8% 43%	2389
	11th to 20th	Day	16% 8% 2 5% 3 4 4 3 5% 7% 43%	2098
	21st to end	Day	10% 7% 2 6% 4 6% 4 3 7% 8% 42%	2090
October	1st to 10th	Day	9% 9% 3 9% 5% 4 4 4 6% 7% 40%	3336
	11th to 20th	Day	10% 11% 4 9% 4 5% 5% 3 6% 9% 34%	2849
	21st to end	Day	8% 11% 3 8% 6% 6% 5% 3 5% 7% 38%	3101
November	1st to 10th	Day	9% 16% 4 10% 8% 6% 5% 4 6% 7% 25%	1582
	11th to 20th	Day	6% 14% 4 11% 7% 4 5% 3 5% 6% 33%	1426
	21st to end	Day	6% 12% 5% 12% 7% 8% 4 4 7% 9% 29%	1400
December	1st to 10th	Day	6% 13% 5% 12% 9% 7% 6% 3 6% 6% 27%	1337
	11th to 20th	Day	5% 11% 5% 12% 8% 7% 5% 5% 7% 8% 28%	1682
	21st to end	Day	3 9% 3 9% 5% 5% 6% 4 7% 9% 41%	2442
January	1st to 10th	Night	4 12% 6% 14% 8% 6% 5% 4 6% 6% 29%	4726
	11th to 20th	Night	4 9% 4 12% 8% 6% 5% 6% 7% 6% 32%	4699
	21st to end	Night	7% 14% 5% 10% 7% 5% 5% 4 6% 7% 31%	4986
February	1st to 10th	Night	6% 14% 6% 12% 8% 6% 6% 4 5% 7% 27%	2660
	11th to 20th	Night	6% 15% 4 11% 7% 7% 6% 5% 7% 7% 27%	2470
	21st to end	Night	5% 13% 5% 11% 7% 6% 6% 4 6% 7% 30%	1955
March	1st to 10th	Night	3 10% 5% 14% 8% 8% 6% 4 6% 9% 28%	3736
	11th to 20th	Night	6% 10% 3 7% 5% 5% 6% 5% 7% 10% 37%	3557
	21st to end	Night	5% 17% 7% 16% 7% 6% 6% 4 6% 6% 20%	3722
April	1st to 10th	Night	9% 10% 4 10% 8% 6% 6% 5% 8% 7% 27%	1832
	11th to 20th	Night	10% 13% 4 9% 8% 5% 6% 5% 6% 7% 27%	1691
	21st to end	Night	13% 11% 3 9% 5% 4 4 4 6% 8% 34%	1710
May	1st to 10th	Night	23% 12% 4 8% 5% 4 4 3 4 6% 28%	2367
	11th to 20th	Night	13% 8% 3 10% 6% 6% 5% 5% 7% 8% 29%	2199
	21st to end	Night	15% 10% 3 9% 6% 7% 6% 5% 7% 7% 25%	2414
June	1st to 10th	Night	18% 6% 3 10% 4 6% 5% 5% 8% 8% 27%	1330
	11th to 20th	Night	18% 8% 4 9% 6% 7% 6% 5% 6% 6% 23%	1246
	21st to end	Night	12% 7% 2 7% 5% 6% 6% 6% 9% 7% 33%	1140
July	1st to 10th	Night	10% 6% 3 7% 4 5% 5% 4 6% 8% 43%	2111
	11th to 20th	Night	8% 6% 3 7% 5% 5% 5% 5% 7% 10% 38%	2220
	21st to end	Night	14% 6% 2 6% 4 4 5% 5% 7% 8% 40%	2414
August	1st to 10th	Night	14% 6% 2 6% 5% 5% 5% 5% 6% 9% 38%	2492
	11th to 20th	Night	11% 7% 3 6% 5% 5% 5% 5% 7% 9% 37%	2657
	21st to end	Night	13% 5% 2 6% 5% 5% 5% 4 7% 9% 40%	3146
September	1st to 10th	Night	13% 5% 2 7% 4 4 5% 3 6% 7% 44%	1787
	11th to 20th	Night	13% 6% 3 7% 4 5% 4 4 6% 7% 42%	2081
	21st to end	Night	10% 7% 2 6% 4 4 4 3 7% 8% 43%	2090
October	1st to 10th	Night	9% 8% 3 7% 5% 4 6% 4 6% 8% 40%	3639
	11th to 20th	Night	10% 8% 4 7% 4 5% 6% 4 7% 9% 37%	4076
	21st to end	Night	6% 11% 4 9% 6% 6% 5% 4 6% 7% 36%	4457
November	1st to 10th	Night	11% 16% 5% 10% 6% 5% 5% 4 5% 7% 26%	2697
	11th to 20th	Night	7% 14% 5% 12% 7% 6% 5% 4 7% 7% 27%	2970
	21st to end	Night	7% 14% 4 11% 8% 5% 6% 5% 6% 9% 28%	3000
December	1st to 10th	Night	7% 15% 5% 10% 7% 5% 4 4 6% 6% 30%	2878
	11th to 20th	Night	5% 12% 6% 11% 7% 6% 5% 5% 6% 7% 28%	3510
	21st to end	Night	4 9% 4 8% 6% 6% 5% 4 5% 8% 43%	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	50% 5% 14% 21% 8% 1	2219
	11th to 20th	Day	47% 3 11% 16% 20% 3	2220
	21st to end	Day	48% 4 16% 26% 6% 1	2698
February	1st to 10th	Day	55% 4 14% 15% 10% 1	1520
	11th to 20th	Day	53% 5% 15% 18% 9% 1	1604
	21st to end	Day	56% 5% 12% 18% 9% 1	1498
March	1st to 10th	Day	56% 5% 13% 17% 9%	3138
	11th to 20th	Day	36% 6% 19% 22% 17% 1	3423
	21st to end	Day	57% 7% 11% 19% 6%	3917
April	1st to 10th	Day	50% 8% 15% 19% 8% 1	2348
	11th to 20th	Day	52% 5% 12% 23% 8%	2440
	21st to end	Day	49% 5% 14% 23% 7% 2	2470
May	1st to 10th	Day	53% 4 11% 23% 7%	4593
	11th to 20th	Day	50% 5% 13% 23% 8%	4698
	21st to end	Day	50% 5% 19% 18% 8%	5162
June	1st to 10th	Day	48% 5% 17% 23% 7% 1	2850
	11th to 20th	Day	55% 6% 16% 16% 6%	2927
	21st to end	Day	37% 7% 24% 24% 6% 1	3040
July	1st to 10th	Day	32% 5% 16% 32% 14% 2	4770
	11th to 20th	Day	32% 6% 18% 33% 11%	4659
	21st to end	Day	36% 5% 21% 23% 13% 2	4976
August	1st to 10th	Day	39% 6% 20% 32% 2	4418
	11th to 20th	Day	35% 6% 23% 28% 7%	4218
	21st to end	Day	38% 6% 27% 24% 5%	4520
September	1st to 10th	Day	38% 5% 21% 26% 8% 2	2389
	11th to 20th	Day	41% 4 18% 29% 8%	2098
	21st to end	Day	39% 6% 17% 25% 10% 2	2090
October	1st to 10th	Day	43% 4 22% 26% 5% 1	3336
	11th to 20th	Day	46% 4 14% 25% 10%	2849
	21st to end	Day	46% 4 16% 28% 5%	3101
November	1st to 10th	Day	57% 5% 15% 16% 6% 1	1582
	11th to 20th	Day	52% 5% 15% 19% 9%	1426
	21st to end	Day	53% 5% 17% 17% 6% 2	1400
December	1st to 10th	Day	57% 5% 12% 16% 8% 2	1337
	11th to 20th	Day	53% 4 18% 18% 7% 1	1684
	21st to end	Day	39% 4 14% 21% 18% 3	2442
January	1st to 10th	Night	54% 4 14% 18% 8% 2	4726
	11th to 20th	Night	49% 4 12% 14% 18% 4	4740
	21st to end	Night	52% 3 17% 20% 8% 1	4986
February	1st to 10th	Night	56% 3 11% 19% 9% 1	2660
	11th to 20th	Night	54% 6% 13% 16% 11% 1	2472
	21st to end	Night	52% 4 11% 21% 10% 1	1955
March	1st to 10th	Night	52% 6% 12% 20% 11%	3736
	11th to 20th	Night	40% 5% 19% 20% 14% 1	3557
	21st to end	Night	62% 7% 10% 16% 5%	3722
April	1st to 10th	Night	51% 8% 13% 18% 9% 1	1832
	11th to 20th	Night	53% 5% 12% 19% 9% 2	1691
	21st to end	Night	48% 5% 14% 22% 9% 1	1710
May	1st to 10th	Night	57% 5% 8% 21% 9%	2367
	11th to 20th	Night	50% 5% 15% 22% 8% 1	2199
	21st to end	Night	55% 4 18% 14% 8% 1	2414
June	1st to 10th	Night	52% 6% 15% 20% 7% 1	1330
	11th to 20th	Night	58% 6% 16% 15% 5%	1246
	21st to end	Night	45% 8% 21% 21% 5% 1	1140
July	1st to 10th	Night	37% 6% 17% 23% 16% 1	2076
	11th to 20th	Night	39% 8% 17% 27% 9% 1	2178
	21st to end	Night	40% 7% 19% 24% 9% 1	2337
August	1st to 10th	Night	42% 6% 21% 29% 2	2485
	11th to 20th	Night	41% 7% 22% 22% 8% 1	2681
	21st to end	Night	39% 5% 21% 29% 6%	3146
September	1st to 10th	Night	38% 5% 18% 25% 12% 2	1787
	11th to 20th	Night	42% 4 16% 28% 8% 3	2081
	21st to end	Night	37% 5% 16% 26% 14% 2	2090
October	1st to 10th	Night	43% 4 20% 26% 8%	3639
	11th to 20th	Night	43% 4 13% 31% 8% 1	4076
	21st to end	Night	46% 5% 16% 26% 7% 1	4457
November	1st to 10th	Night	56% 5% 12% 19% 7%	2697
	11th to 20th	Night	54% 5% 13% 18% 8% 1	2970
	21st to end	Night	53% 6% 16% 18% 6% 2	3000
December	1st to 10th	Night	53% 5% 11% 20% 9% 2	2878
	11th to 20th	Night	53% 5% 16% 19% 7%	3507
	21st to end	Night	40% 3 13% 24% 16% 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	6% 4 33% 33% 19% 6%	180
	11th to 20th	Day	11% 4 38% 27% 12% 8%	180
	21st to end	Day	11% 9% 29% 31% 15% 5%	198
February	1st to 10th	Day	16% 9% 32% 26% 13% 3	180
	11th to 20th	Day	13% 6% 32% 32% 14% 4	236
	21st to end	Day	8% 6% 34% 31% 15% 6%	310
March	1st to 10th	Day	11% 9% 30% 29% 18% 3	460
	11th to 20th	Day	10% 5% 34% 31% 14% 6%	460
	21st to end	Day	15% 7% 28% 28% 18% 4	506
April	1st to 10th	Day	11% 11% 34% 29% 13% 2	460
	11th to 20th	Day	17% 6% 24% 31% 16% 7%	452
	21st to end	Day	17% 8% 25% 28% 16% 5%	460
May	1st to 10th	Day	17% 6% 21% 33% 18% 5%	572
	11th to 20th	Day	12% 5% 21% 35% 21% 7%	675
	21st to end	Day	17% 4 18% 29% 23% 9%	734
June	1st to 10th	Day	17% 6% 24% 33% 17% 4	680
	11th to 20th	Day	20% 5% 21% 27% 21% 6%	757
	21st to end	Day	12% 4 19% 30% 25% 10%	870
July	1st to 10th	Day	13% 3 16% 35% 24% 9%	736
	11th to 20th	Day	13% 4 18% 31% 26% 9%	668
	21st to end	Day	12% 5% 14% 29% 27% 13%	739
August	1st to 10th	Day	11% 5% 16% 30% 25% 14%	509
	11th to 20th	Day	9% 4 22% 31% 26% 9%	477
	21st to end	Day	15% 7% 16% 27% 25% 10%	539
September	1st to 10th	Day	15% 5% 25% 26% 20% 9%	490
	11th to 20th	Day	19% 6% 19% 31% 19% 6%	490
	21st to end	Day	14% 11% 30% 23% 16% 5%	490
October	1st to 10th	Day	15% 8% 25% 28% 16% 7%	401
	11th to 20th	Day	13% 9% 31% 29% 13% 5%	300
	21st to end	Day	14% 12% 35% 26% 11% 3	330
November	1st to 10th	Day	19% 5% 32% 29% 11% 4	300
	11th to 20th	Day	15% 6% 34% 33% 9% 3	213
	21st to end	Day	8% 6% 39% 29% 14% 5%	200
December	1st to 10th	Day	11% 6% 36% 27% 13% 7%	182
	11th to 20th	Day	10% 12% 32% 30% 13% 3	180
	21st to end	Day	7% 4 30% 34% 17% 8%	198
January	1st to 10th	Night	11% 7% 35% 30% 15% 1	950
	11th to 20th	Night	12% 8% 35% 33% 10% 2	950
	21st to end	Night	13% 11% 33% 31% 10% 2	908
February	1st to 10th	Night	11% 9% 27% 33% 18% 2	760
	11th to 20th	Night	12% 6% 33% 34% 14% 1	744
	21st to end	Night	11% 7% 27% 34% 17% 5%	628
March	1st to 10th	Night	9% 5% 32% 35% 15% 3	760
	11th to 20th	Night	11% 5% 34% 33% 15% 2	760
	21st to end	Night	13% 4 28% 38% 16% 2	836
April	1st to 10th	Night	12% 7% 28% 37% 13% 2	692
	11th to 20th	Night	17% 5% 26% 37% 14% 1	563
	21st to end	Night	16% 6% 25% 38% 13% 1	570
May	1st to 10th	Night	20% 6% 21% 38% 13% 3	394
	11th to 20th	Night	14% 5% 24% 36% 19% 2	374
	21st to end	Night	20% 6% 19% 35% 18% 2	411
June	1st to 10th	Night	20% 6% 25% 33% 14% 2	380
	11th to 20th	Night	21% 3 20% 37% 17% 2	380
	21st to end	Night	15% 4 19% 35% 23% 4	380
July	1st to 10th	Night	14% 2 13% 46% 25% 1	370
	11th to 20th	Night	12% 4 16% 45% 21% 2	368
	21st to end	Night	15% 2 13% 38% 29% 3	416
August	1st to 10th	Night	15% 3 18% 31% 27% 7%	378
	11th to 20th	Night	11% 4 17% 37% 28% 3	471
	21st to end	Night	14% 3 20% 40% 23% 1	627
September	1st to 10th	Night	14% 2 20% 42% 19% 2	647
	11th to 20th	Night	14% 4 21% 39% 20% 2	760
	21st to end	Night	14% 4 29% 36% 14% 2	760
October	1st to 10th	Night	15% 4 29% 37% 14% 1	760
	11th to 20th	Night	16% 6% 33% 30% 14% 2	760
	21st to end	Night	12% 8% 35% 32% 12%	836
November	1st to 10th	Night	19% 6% 33% 31% 9% 1	942
	11th to 20th	Night	12% 7% 40% 30% 9% 2	1000
	21st to end	Night	13% 5% 40% 29% 11% 2	1000
December	1st to 10th	Night	14% 9% 33% 30% 12% 3	960
	11th to 20th	Night	11% 6% 36% 33% 13% 1	950
	21st to end	Night	11% 4 34% 32% 16% 2	1045

Page generated at 2024-11-29 08:43:08. Version ac07

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