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 2024-01-15.

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% 4 7% 7% 4 5% 6% 6% 8% 34%	74951
	Night	9% 10% 5% 8% 7% 4 5% 6% 6% 8% 32%	74823
Transparency	Day	46% 5% 18% 22% 8% 1	74631
	Night	49% 5% 15% 21% 9% 1	74661
Seeing	Day	14% 6% 24% 30% 19% 7%	14566
	Night	14% 6% 29% 34% 15% 2	23419

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	5% 11% 5% 10% 10% 5% 6% 8% 7% 7% 28%	1329
	11th to 20th	Day	7% 12% 5% 10% 7% 3 5% 5% 5% 9% 33%	1288
	21st to end	Day	6% 14% 7% 11% 7% 4 7% 5% 6% 7% 25%	1530
February	1st to 10th	Day	9% 12% 4 10% 8% 4 6% 5% 8% 8% 25%	1440
	11th to 20th	Day	5% 14% 6% 12% 7% 4 6% 5% 7% 7% 27%	1510
	21st to end	Day	3 11% 7% 11% 10% 5% 7% 7% 5% 9% 24%	1412
March	1st to 10th	Day	6% 13% 5% 11% 10% 4 6% 6% 6% 6% 27%	1800
	11th to 20th	Day	7% 11% 5% 7% 6% 3 5% 6% 7% 9% 34%	1938
	21st to end	Day	8% 15% 5% 8% 7% 3 6% 5% 7% 9% 26%	2232
April	1st to 10th	Day	9% 11% 5% 8% 9% 4 5% 6% 7% 8% 28%	2224
	11th to 20th	Day	12% 13% 5% 9% 6% 4 4 6% 6% 8% 27%	2310
	21st to end	Day	12% 9% 3 8% 7% 4 6% 6% 6% 9% 31%	2340
May	1st to 10th	Day	13% 10% 4 7% 7% 4 7% 6% 6% 8% 28%	2609
	11th to 20th	Day	9% 6% 3 6% 6% 4 5% 5% 6% 9% 40%	2654
	21st to end	Day	18% 7% 3 6% 5% 4 5% 5% 6% 8% 33%	2917
June	1st to 10th	Day	17% 7% 4 5% 6% 4 5% 5% 7% 9% 31%	2700
	11th to 20th	Day	19% 9% 3 7% 7% 5% 7% 6% 6% 7% 25%	2772
	21st to end	Day	10% 5% 2 5% 6% 4 5% 7% 8% 10% 39%	2880
July	1st to 10th	Day	11% 7% 3 6% 6% 3 6% 6% 7% 10% 37%	2762
	11th to 20th	Day	12% 6% 2 5% 6% 4 6% 6% 7% 9% 37%	2700
	21st to end	Day	10% 4 2 5% 5% 3 6% 6% 6% 9% 45%	2938
August	1st to 10th	Day	10% 6% 2 6% 6% 3 6% 6% 7% 10% 38%	2528
	11th to 20th	Day	9% 5% 2 5% 5% 3 4 6% 7% 9% 44%	2386
	21st to end	Day	12% 6% 2 5% 5% 3 5% 6% 6% 9% 42%	2574
September	1st to 10th	Day	13% 6% 2 5% 5% 4 4 5% 6% 8% 41%	2264
	11th to 20th	Day	16% 7% 2 5% 4 3 4 4 5% 7% 43%	1988
	21st to end	Day	11% 7% 2 5% 5% 4 5% 4 7% 8% 42%	1980
October	1st to 10th	Day	11% 10% 3 9% 6% 3 5% 4 5% 5% 38%	1896
	11th to 20th	Day	11% 10% 4 7% 5% 3 5% 4 6% 9% 37%	1627
	21st to end	Day	9% 13% 4 7% 7% 4 7% 4 6% 7% 32%	1782
November	1st to 10th	Day	9% 15% 6% 9% 9% 4 6% 5% 6% 8% 24%	1502
	11th to 20th	Day	7% 12% 5% 10% 8% 3 4 5% 5% 6% 33%	1355
	21st to end	Day	6% 10% 6% 10% 7% 6% 5% 4 7% 9% 31%	1330
December	1st to 10th	Day	6% 12% 6% 11% 10% 4 7% 5% 5% 7% 27%	1330
	11th to 20th	Day	5% 11% 5% 10% 9% 5% 6% 6% 6% 8% 28%	1682
	21st to end	Day	3 8% 3 8% 6% 4 5% 5% 6% 9% 41%	2442
January	1st to 10th	Night	6% 12% 6% 11% 8% 5% 6% 6% 6% 7% 28%	2836
	11th to 20th	Night	7% 11% 5% 10% 7% 4 5% 6% 7% 8% 31%	2767
	21st to end	Night	7% 14% 7% 11% 8% 4 6% 5% 5% 6% 26%	2840
February	1st to 10th	Night	6% 12% 6% 11% 9% 5% 6% 5% 5% 8% 27%	2520
	11th to 20th	Night	6% 14% 5% 9% 9% 5% 6% 7% 7% 7% 25%	2336
	21st to end	Night	6% 11% 6% 10% 8% 5% 7% 5% 6% 7% 30%	1843
March	1st to 10th	Night	6% 11% 5% 8% 9% 5% 6% 5% 6% 9% 28%	2160
	11th to 20th	Night	8% 10% 4 9% 7% 5% 6% 6% 7% 8% 30%	2021
	21st to end	Night	6% 15% 5% 10% 9% 4 5% 6% 7% 8% 26%	2123
April	1st to 10th	Night	9% 10% 4 9% 9% 4 6% 6% 7% 8% 27%	1736
	11th to 20th	Night	11% 12% 5% 8% 9% 4 5% 6% 5% 7% 28%	1601
	21st to end	Night	13% 10% 4 7% 6% 3 4 5% 6% 8% 35%	1620
May	1st to 10th	Night	14% 11% 5% 8% 7% 3 6% 5% 6% 8% 27%	1351
	11th to 20th	Night	11% 9% 3 7% 7% 4 5% 6% 6% 8% 36%	1239
	21st to end	Night	18% 11% 4 5% 5% 4 4 5% 5% 7% 31%	1358
June	1st to 10th	Night	19% 6% 3 7% 6% 3 6% 5% 8% 8% 28%	1260
	11th to 20th	Night	19% 8% 4 8% 7% 5% 6% 7% 6% 7% 23%	1181
	21st to end	Night	13% 6% 3 5% 6% 4 7% 7% 8% 8% 34%	1080
July	1st to 10th	Night	12% 5% 3 6% 5% 4 5% 6% 6% 9% 39%	1193
	11th to 20th	Night	11% 6% 3 5% 7% 4 6% 8% 8% 10% 32%	1260
	21st to end	Night	11% 6% 2 5% 5% 3 5% 6% 7% 9% 40%	1379
August	1st to 10th	Night	12% 5% 2 5% 7% 4 5% 6% 6% 10% 38%	1409
	11th to 20th	Night	10% 5% 3 5% 6% 4 5% 6% 7% 10% 39%	1514
	21st to end	Night	13% 6% 3 5% 4 3 5% 6% 7% 10% 40%	1782
September	1st to 10th	Night	13% 5% 2 6% 6% 3 5% 5% 6% 8% 42%	1692
	11th to 20th	Night	13% 6% 3 6% 5% 3 5% 4 5% 7% 43%	1971
	21st to end	Night	11% 6% 3 5% 5% 3 3 5% 7% 9% 43%	1980
October	1st to 10th	Night	12% 8% 3 7% 7% 3 6% 4 6% 7% 38%	2064
	11th to 20th	Night	11% 9% 4 7% 6% 3 5% 5% 6% 8% 37%	2330
	21st to end	Night	7% 11% 3 9% 9% 4 6% 5% 6% 7% 32%	2574
November	1st to 10th	Night	11% 15% 5% 9% 7% 4 6% 6% 5% 7% 26%	2558
	11th to 20th	Night	8% 12% 6% 10% 8% 4 5% 6% 6% 7% 28%	2821
	21st to end	Night	7% 11% 5% 9% 9% 4 6% 6% 6% 9% 29%	2850
December	1st to 10th	Night	8% 12% 6% 9% 8% 4 5% 5% 5% 7% 31%	2850
	11th to 20th	Night	5% 12% 7% 9% 8% 5% 5% 6% 6% 7% 29%	3510
	21st to end	Night	4 8% 4 7% 7% 4 5% 5% 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	52% 6% 12% 20% 7% 2	1329
	11th to 20th	Day	50% 4 16% 18% 10% 2	1288
	21st to end	Day	58% 5% 13% 16% 7% 1	1530
February	1st to 10th	Day	54% 4 15% 16% 10% 1	1440
	11th to 20th	Day	54% 5% 16% 18% 7%	1518
	21st to end	Day	56% 5% 12% 18% 8% 1	1412
March	1st to 10th	Day	56% 6% 13% 19% 6% 1	1800
	11th to 20th	Day	44% 5% 14% 24% 12% 1	1939
	21st to end	Day	53% 6% 16% 18% 6%	2232
April	1st to 10th	Day	50% 8% 15% 19% 8% 1	2224
	11th to 20th	Day	53% 5% 13% 22% 7%	2310
	21st to end	Day	48% 6% 14% 23% 7% 2	2340
May	1st to 10th	Day	52% 5% 15% 19% 8% 1	2609
	11th to 20th	Day	40% 4 15% 29% 11%	2658
	21st to end	Day	48% 4 16% 21% 10%	2918
June	1st to 10th	Day	48% 5% 18% 23% 6%	2700
	11th to 20th	Day	56% 6% 17% 15% 6%	2772
	21st to end	Day	37% 8% 25% 24% 5% 1	2880
July	1st to 10th	Day	41% 6% 21% 25% 5% 1	2688
	11th to 20th	Day	42% 8% 27% 22% 2	2619
	21st to end	Day	35% 6% 29% 26% 4	2775
August	1st to 10th	Day	40% 7% 27% 24% 3	2510
	11th to 20th	Day	35% 6% 28% 25% 7%	2386
	21st to end	Day	38% 6% 24% 24% 8% 1	2574
September	1st to 10th	Day	40% 5% 21% 25% 7% 2	2264
	11th to 20th	Day	41% 4 18% 29% 9%	1988
	21st to end	Day	39% 6% 17% 25% 10% 2	1980
October	1st to 10th	Day	48% 4 16% 22% 9% 1	1896
	11th to 20th	Day	44% 5% 17% 24% 11%	1627
	21st to end	Day	51% 5% 12% 23% 9% 1	1782
November	1st to 10th	Day	57% 5% 14% 17% 6% 1	1502
	11th to 20th	Day	51% 5% 15% 19% 9%	1355
	21st to end	Day	50% 5% 17% 18% 7% 2	1330
December	1st to 10th	Day	57% 5% 12% 16% 8% 2	1330
	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	55% 5% 14% 16% 8% 2	2836
	11th to 20th	Night	50% 5% 16% 17% 9% 2	2767
	21st to end	Night	59% 4 11% 15% 10% 1	2840
February	1st to 10th	Night	55% 3 11% 19% 9% 1	2520
	11th to 20th	Night	55% 6% 13% 16% 10% 1	2338
	21st to end	Night	52% 4 11% 21% 11% 1	1843
March	1st to 10th	Night	51% 7% 13% 22% 7% 1	2160
	11th to 20th	Night	49% 5% 11% 21% 13% 1	2021
	21st to end	Night	55% 5% 14% 19% 7% 1	2123
April	1st to 10th	Night	51% 8% 13% 19% 8% 1	1736
	11th to 20th	Night	53% 5% 12% 20% 8% 2	1601
	21st to end	Night	47% 5% 15% 23% 9% 1	1620
May	1st to 10th	Night	54% 5% 13% 19% 8% 1	1351
	11th to 20th	Night	46% 5% 12% 24% 13% 1	1239
	21st to end	Night	50% 6% 15% 17% 9% 2	1358
June	1st to 10th	Night	51% 7% 15% 20% 7%	1260
	11th to 20th	Night	58% 6% 17% 14% 4	1181
	21st to end	Night	44% 8% 21% 21% 5% 1	1080
July	1st to 10th	Night	40% 7% 21% 26% 6% 1	1158
	11th to 20th	Night	43% 11% 24% 17% 4	1218
	21st to end	Night	39% 7% 23% 25% 5%	1302
August	1st to 10th	Night	42% 6% 25% 23% 3	1402
	11th to 20th	Night	38% 7% 24% 24% 6% 1	1514
	21st to end	Night	38% 5% 19% 28% 9% 1	1782
September	1st to 10th	Night	39% 6% 18% 25% 10% 2	1692
	11th to 20th	Night	41% 4 16% 28% 9% 3	1971
	21st to end	Night	37% 5% 16% 26% 14% 2	1980
October	1st to 10th	Night	45% 5% 14% 24% 11% 1	2064
	11th to 20th	Night	44% 5% 14% 27% 9% 1	2330
	21st to end	Night	51% 5% 14% 22% 8% 1	2574
November	1st to 10th	Night	57% 5% 12% 18% 8%	2558
	11th to 20th	Night	53% 6% 13% 19% 9% 1	2821
	21st to end	Night	51% 6% 16% 18% 6% 2	2850
December	1st to 10th	Night	53% 5% 11% 20% 9% 2	2850
	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 35% 28% 13% 10%	168
	21st to end	Day	12% 9% 30% 31% 14% 5%	176
February	1st to 10th	Day	14% 10% 33% 28% 13% 3	160
	11th to 20th	Day	14% 7% 33% 32% 11% 2	210
	21st to end	Day	8% 5% 32% 32% 16% 6%	278
March	1st to 10th	Day	12% 9% 29% 29% 17% 3	420
	11th to 20th	Day	10% 5% 34% 31% 14% 6%	420
	21st to end	Day	15% 7% 29% 26% 19% 4	462
April	1st to 10th	Day	11% 9% 34% 30% 13% 3	420
	11th to 20th	Day	19% 5% 22% 32% 16% 7%	412
	21st to end	Day	17% 8% 26% 27% 17% 5%	420
May	1st to 10th	Day	16% 6% 21% 32% 19% 6%	526
	11th to 20th	Day	11% 5% 20% 35% 22% 7%	625
	21st to end	Day	18% 4 17% 30% 23% 8%	679
June	1st to 10th	Day	18% 6% 22% 33% 17% 4	630
	11th to 20th	Day	21% 5% 20% 27% 22% 5%	702
	21st to end	Day	12% 4 18% 30% 25% 11%	810
July	1st to 10th	Day	13% 3 16% 34% 24% 9%	683
	11th to 20th	Day	13% 4 19% 31% 25% 8%	618
	21st to end	Day	11% 4 14% 30% 28% 13%	684
August	1st to 10th	Day	11% 4 16% 29% 24% 14%	468
	11th to 20th	Day	9% 4 22% 30% 27% 8%	437
	21st to end	Day	16% 6% 15% 28% 25% 10%	495
September	1st to 10th	Day	16% 5% 26% 27% 19% 7%	450
	11th to 20th	Day	20% 6% 19% 30% 20% 6%	450
	21st to end	Day	15% 10% 28% 24% 17% 6%	450
October	1st to 10th	Day	16% 8% 25% 28% 17% 8%	366
	11th to 20th	Day	14% 9% 31% 29% 13% 4	270
	21st to end	Day	14% 12% 35% 26% 10% 2	297
November	1st to 10th	Day	19% 5% 30% 29% 11% 4	270
	11th to 20th	Day	15% 6% 33% 34% 8% 4	192
	21st to end	Day	7% 7% 41% 28% 13% 5%	180
December	1st to 10th	Day	11% 6% 36% 28% 13% 7%	180
	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% 11% 2	923
	21st to end	Night	14% 11% 34% 30% 10% 2	860
February	1st to 10th	Night	11% 9% 28% 32% 18% 1	720
	11th to 20th	Night	12% 6% 34% 33% 13% 1	704
	21st to end	Night	11% 5% 26% 35% 18% 5%	592
March	1st to 10th	Night	10% 5% 33% 34% 15% 3	720
	11th to 20th	Night	12% 5% 33% 33% 15% 2	720
	21st to end	Night	13% 4 27% 39% 16% 2	792
April	1st to 10th	Night	12% 7% 28% 37% 14% 2	656
	11th to 20th	Night	18% 5% 27% 36% 14% 1	533
	21st to end	Night	16% 6% 25% 38% 13% 1	540
May	1st to 10th	Night	19% 6% 20% 39% 14% 3	374
	11th to 20th	Night	14% 5% 23% 36% 19% 2	354
	21st to end	Night	21% 6% 19% 34% 17% 2	389
June	1st to 10th	Night	21% 6% 23% 34% 14% 3	360
	11th to 20th	Night	22% 3 19% 37% 17% 2	360
	21st to end	Night	14% 4 19% 35% 23% 4	360
July	1st to 10th	Night	14% 2 12% 45% 25% 1	350
	11th to 20th	Night	12% 4 17% 45% 20% 2	348
	21st to end	Night	14% 2 13% 40% 28% 3	394
August	1st to 10th	Night	15% 2 19% 30% 27% 8%	358
	11th to 20th	Night	11% 4 17% 37% 28% 3	446
	21st to end	Night	13% 3 19% 40% 24% 2	594
September	1st to 10th	Night	15% 2 20% 41% 20% 2	612
	11th to 20th	Night	15% 4 22% 38% 20% 2	720
	21st to end	Night	14% 3 28% 38% 15% 2	720
October	1st to 10th	Night	15% 4 28% 37% 15% 1	720
	11th to 20th	Night	16% 6% 33% 29% 15% 2	720
	21st to end	Night	12% 8% 34% 34% 11%	792
November	1st to 10th	Night	19% 6% 33% 32% 9% 1	893
	11th to 20th	Night	13% 7% 39% 29% 10% 2	950
	21st to end	Night	13% 5% 40% 30% 11% 2	950
December	1st to 10th	Night	14% 9% 33% 30% 12% 3	950
	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 2024-01-12 05:31:46. Version ac07

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