Pincher Creek
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pincher Creek clear sky chart from 2005-11-06 to 2026-07-01.

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	6% 7% 3 6% 4 4 4 4 6% 9% 46%	141864
	Night	5% 7% 3 7% 4 4 5% 4 6% 8% 46%	139165
Transparency	Day	35% 5% 15% 28% 15% 3	141575
	Night	36% 5% 17% 26% 13% 2	139037
Seeing	Day	20% 17% 27% 22% 11% 3	17445
	Night	17% 19% 30% 24% 10% 1	26592

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 8% 4 10% 6% 5% 4 4 7% 10% 40%	4125
	11th to 20th	Day	1 7% 5% 10% 6% 6% 5% 4 6% 10% 41%	4455
	21st to end	Day	1 8% 3 10% 5% 4 4 3 5% 10% 47%	5186
February	1st to 10th	Day	3 9% 4 11% 6% 6% 6% 4 7% 10% 34%	1721
	11th to 20th	Day	2 13% 4 10% 6% 4 5% 4 7% 9% 36%	1845
	21st to end	Day	2 9% 5% 11% 7% 4 4 4 7% 9% 39%	1717
March	1st to 10th	Day	2 8% 3 6% 4 4 4 4 7% 12% 46%	4618
	11th to 20th	Day	2 8% 2 6% 4 4 5% 5% 8% 9% 47%	5064
	21st to end	Day	6% 15% 7% 11% 4 4 5% 4 7% 9% 28%	5651
April	1st to 10th	Day	5% 12% 4 7% 5% 4 5% 4 7% 10% 36%	2557
	11th to 20th	Day	8% 12% 3 8% 5% 4 5% 4 7% 7% 36%	2700
	21st to end	Day	10% 12% 3 7% 5% 4 4 4 6% 8% 36%	2730
May	1st to 10th	Day	10% 11% 3 6% 4 4 4 4 6% 7% 41%	7697
	11th to 20th	Day	10% 7% 2 7% 5% 5% 5% 5% 8% 9% 36%	8688
	21st to end	Day	11% 5% 2 5% 4 4 5% 5% 7% 10% 43%	9649
June	1st to 10th	Day	12% 7% 3 7% 5% 5% 5% 4 6% 8% 38%	3150
	11th to 20th	Day	14% 7% 3 6% 5% 6% 6% 5% 7% 7% 34%	3150
	21st to end	Day	8% 4 2 5% 4 4 5% 4 6% 9% 49%	3150
July	1st to 10th	Day	6% 3 1 4 3 4 4 4 6% 8% 57%	6781
	11th to 20th	Day	7% 4 1 4 2 3 4 4 6% 8% 58%	6780
	21st to end	Day	7% 4 1 3 2 3 3 3 5% 7% 62%	6994
August	1st to 10th	Day	10% 5% 2 5% 3 4 4 4 7% 8% 47%	4497
	11th to 20th	Day	5% 3 1 3 3 3 5% 4 6% 8% 59%	4158
	21st to end	Day	7% 3 1 3 2 3 3 3 5% 7% 61%	4664
September	1st to 10th	Day	11% 4 2 4 3 3 4 3 6% 7% 54%	2440
	11th to 20th	Day	10% 5% 1 5% 4 4 4 3 5% 8% 52%	2200
	21st to end	Day	9% 6% 1 4 3 4 3 3 5% 7% 55%	2200
October	1st to 10th	Day	7% 6% 2 4 3 3 4 3 5% 10% 53%	3475
	11th to 20th	Day	3 6% 2 5% 3 4 4 4 7% 9% 53%	3045
	21st to end	Day	6% 7% 3 5% 4 4 4 4 6% 8% 49%	3200
November	1st to 10th	Day	6% 11% 3 7% 3 4 4 4 7% 10% 42%	1780
	11th to 20th	Day	3 8% 3 6% 4 4 5% 4 7% 9% 47%	1680
	21st to end	Day	2 11% 5% 9% 6% 4 4 4 6% 9% 40%	1470
December	1st to 10th	Day	1 5% 3 5% 5% 4 4 4 6% 10% 52%	2360
	11th to 20th	Day	3 8% 3 9% 5% 5% 5% 3 7% 10% 42%	2712
	21st to end	Day	2 8% 4 8% 5% 6% 4 4 6% 9% 44%	3575
January	1st to 10th	Night	2 8% 4 10% 5% 4 4 4 7% 9% 41%	8768
	11th to 20th	Night	1 7% 4 9% 6% 5% 6% 5% 6% 9% 41%	8499
	21st to end	Night	1 7% 3 9% 5% 5% 5% 4 7% 9% 44%	8994
February	1st to 10th	Night	3 12% 4 11% 6% 5% 5% 4 6% 8% 35%	2898
	11th to 20th	Night	2 12% 4 9% 5% 5% 6% 4 6% 9% 37%	2662
	21st to end	Night	2 8% 4 10% 7% 6% 6% 4 5% 7% 41%	2086
March	1st to 10th	Night	2 7% 4 10% 6% 6% 6% 4 6% 8% 43%	5496
	11th to 20th	Night	2 6% 2 6% 4 4 6% 5% 7% 9% 49%	5142
	21st to end	Night	6% 18% 6% 10% 4 4 4 4 6% 9% 28%	5552
April	1st to 10th	Night	8% 10% 3 7% 4 4 5% 4 6% 8% 42%	2062
	11th to 20th	Night	8% 10% 4 7% 4 4 4 5% 7% 8% 39%	1871
	21st to end	Night	7% 12% 4 7% 6% 4 4 3 7% 7% 39%	1890
May	1st to 10th	Night	12% 10% 3 6% 4 4 4 3 5% 7% 42%	5231
	11th to 20th	Night	9% 7% 3 7% 5% 5% 4 4 6% 9% 40%	4170
	21st to end	Night	11% 5% 2 6% 4 4 5% 4 7% 7% 44%	4522
June	1st to 10th	Night	12% 6% 2 6% 5% 4 4 4 6% 9% 42%	1470
	11th to 20th	Night	15% 6% 2 5% 4 5% 4 4 6% 8% 40%	1470
	21st to end	Night	7% 3 2 5% 4 3 5% 4 6% 8% 54%	1470
July	1st to 10th	Night	5% 2 1 2 2 3 4 4 6% 8% 63%	3180
	11th to 20th	Night	6% 2 1 4 3 3 3 3 6% 7% 63%	3180
	21st to end	Night	11% 4 2 4 3 2 2 2 3 5% 62%	3832
August	1st to 10th	Night	11% 4 2 4 3 3 4 3 5% 8% 53%	2641
	11th to 20th	Night	5% 3 1 4 4 4 5% 4 8% 10% 52%	2901
	21st to end	Night	5% 2 1 3 3 3 3 4 6% 7% 62%	3245
September	1st to 10th	Night	9% 4 1 4 3 3 4 3 5% 6% 58%	1956
	11th to 20th	Night	11% 6% 2 4 2 3 3 3 5% 7% 54%	2200
	21st to end	Night	9% 6% 2 3 3 3 4 4 5% 7% 55%	2200
October	1st to 10th	Night	7% 5% 1 3 2 3 3 3 5% 8% 59%	3720
	11th to 20th	Night	3 4 2 3 3 3 3 3 7% 11% 57%	4088
	21st to end	Night	3 6% 3 6% 4 3 4 3 6% 7% 54%	4600
November	1st to 10th	Night	5% 12% 3 7% 5% 5% 4 4 7% 8% 41%	2718
	11th to 20th	Night	2 7% 3 7% 4 4 5% 5% 7% 9% 47%	2940
	21st to end	Night	2 10% 4 7% 5% 4 4 3 6% 10% 42%	3148
December	1st to 10th	Night	2 6% 3 8% 5% 4 5% 5% 7% 10% 46%	5040
	11th to 20th	Night	2 9% 4 9% 6% 5% 6% 5% 8% 9% 36%	5700
	21st to end	Night	1 10% 5% 9% 5% 5% 5% 4 6% 8% 42%	7623

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	39% 5% 17% 23% 15% 1	4125
	11th to 20th	Day	40% 4 20% 21% 12% 4	4478
	21st to end	Day	35% 5% 16% 31% 12%	5187
February	1st to 10th	Day	45% 6% 17% 20% 10% 2	1721
	11th to 20th	Day	44% 6% 18% 20% 10% 2	1854
	21st to end	Day	42% 7% 16% 23% 12% 1	1717
March	1st to 10th	Day	30% 6% 13% 29% 20% 2	4618
	11th to 20th	Day	32% 5% 16% 30% 15% 1	5065
	21st to end	Day	51% 7% 16% 18% 7%	5651
April	1st to 10th	Day	42% 6% 17% 24% 9% 1	2557
	11th to 20th	Day	44% 6% 15% 23% 10% 1	2700
	21st to end	Day	45% 6% 14% 22% 12% 1	2730
May	1st to 10th	Day	42% 3 10% 27% 16% 3	7697
	11th to 20th	Day	40% 6% 11% 28% 12% 2	8692
	21st to end	Day	36% 5% 15% 30% 14%	9650
June	1st to 10th	Day	43% 7% 14% 22% 13% 2	3150
	11th to 20th	Day	46% 6% 12% 21% 13% 2	3150
	21st to end	Day	31% 5% 16% 31% 14% 3	3150
July	1st to 10th	Day	26% 3 13% 25% 24% 9%	6707
	11th to 20th	Day	26% 3 12% 32% 20% 7%	6699
	21st to end	Day	23% 2 12% 29% 21% 13%	6798
August	1st to 10th	Day	34% 4 15% 25% 19% 5%	4480
	11th to 20th	Day	23% 3 19% 36% 16% 3	4197
	21st to end	Day	23% 4 9% 40% 21% 3	4663
September	1st to 10th	Day	29% 4 12% 28% 18% 8%	2440
	11th to 20th	Day	32% 5% 13% 30% 16% 4	2200
	21st to end	Day	29% 5% 14% 33% 15% 3	2200
October	1st to 10th	Day	28% 4 16% 37% 14% 1	3475
	11th to 20th	Day	28% 4 21% 29% 17% 1	3045
	21st to end	Day	33% 4 15% 31% 13% 3	3200
November	1st to 10th	Day	38% 9% 17% 23% 11% 1	1780
	11th to 20th	Day	33% 9% 22% 26% 9% 1	1680
	21st to end	Day	40% 8% 22% 20% 8% 2	1470
December	1st to 10th	Day	29% 6% 27% 29% 8% 2	2360
	11th to 20th	Day	37% 6% 26% 24% 7% 1	2714
	21st to end	Day	37% 5% 16% 25% 17% 1	3575
January	1st to 10th	Night	39% 6% 17% 26% 11% 1	8769
	11th to 20th	Night	41% 4 18% 22% 12% 3	8538
	21st to end	Night	36% 6% 21% 27% 11%	8994
February	1st to 10th	Night	47% 7% 14% 18% 13% 2	2898
	11th to 20th	Night	43% 8% 17% 21% 11% 1	2663
	21st to end	Night	43% 6% 15% 26% 9% 2	2086
March	1st to 10th	Night	36% 7% 15% 25% 15% 3	5496
	11th to 20th	Night	30% 7% 20% 28% 15% 1	5142
	21st to end	Night	51% 6% 19% 17% 6%	5552
April	1st to 10th	Night	39% 7% 17% 26% 10% 1	2062
	11th to 20th	Night	41% 7% 13% 30% 9%	1871
	21st to end	Night	42% 7% 13% 28% 9% 1	1890
May	1st to 10th	Night	43% 3 12% 28% 12% 2	5228
	11th to 20th	Night	39% 6% 11% 31% 13%	4170
	21st to end	Night	38% 5% 14% 31% 12% 1	4526
June	1st to 10th	Night	39% 6% 16% 27% 11% 1	1470
	11th to 20th	Night	41% 4 16% 23% 14% 1	1470
	21st to end	Night	28% 4 18% 32% 16% 3	1470
July	1st to 10th	Night	20% 3 18% 26% 25% 9%	3145
	11th to 20th	Night	22% 3 17% 31% 19% 9%	3138
	21st to end	Night	28% 2 15% 24% 20% 12%	3723
August	1st to 10th	Night	31% 3 15% 27% 17% 8%	2633
	11th to 20th	Night	27% 3 19% 33% 16% 2	2928
	21st to end	Night	21% 3 9% 40% 23% 3	3245
September	1st to 10th	Night	26% 5% 12% 33% 17% 7%	1956
	11th to 20th	Night	30% 4 15% 30% 18% 4	2200
	21st to end	Night	28% 4 18% 31% 16% 3	2200
October	1st to 10th	Night	25% 3 13% 35% 22% 2	3720
	11th to 20th	Night	22% 4 23% 30% 19% 2	4088
	21st to end	Night	30% 5% 15% 38% 11% 1	4600
November	1st to 10th	Night	40% 6% 19% 22% 11% 1	2718
	11th to 20th	Night	33% 8% 23% 24% 12% 1	2940
	21st to end	Night	38% 7% 23% 20% 9% 2	3148
December	1st to 10th	Night	33% 6% 25% 24% 11% 2	5040
	11th to 20th	Night	42% 8% 23% 21% 6%	5697
	21st to end	Night	40% 4 17% 22% 13% 3	7623

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	23% 21% 25% 17% 10% 4	220
	11th to 20th	Day	28% 17% 26% 20% 7% 1	220
	21st to end	Day	25% 31% 25% 11% 6% 2	242
February	1st to 10th	Day	26% 16% 31% 16% 9% 1	242
	11th to 20th	Day	18% 22% 28% 23% 8% 1	330
	21st to end	Day	23% 27% 28% 18% 4 1	433
March	1st to 10th	Day	22% 20% 29% 19% 7% 3	540
	11th to 20th	Day	22% 22% 26% 18% 10% 1	540
	21st to end	Day	24% 22% 29% 16% 7% 2	594
April	1st to 10th	Day	24% 23% 28% 19% 6% 1	540
	11th to 20th	Day	22% 23% 28% 16% 9% 2	532
	21st to end	Day	23% 21% 24% 20% 10% 2	540
May	1st to 10th	Day	18% 16% 28% 22% 12% 3	543
	11th to 20th	Day	25% 13% 23% 22% 13% 3	746
	21st to end	Day	23% 9% 23% 25% 15% 5%	844
June	1st to 10th	Day	21% 18% 26% 23% 10% 2	780
	11th to 20th	Day	25% 18% 24% 22% 9% 2	780
	21st to end	Day	12% 11% 30% 28% 16% 3	780
July	1st to 10th	Day	11% 9% 29% 29% 19% 4	722
	11th to 20th	Day	11% 13% 26% 31% 15% 3	718
	21st to end	Day	9% 11% 32% 29% 16% 3	630
August	1st to 10th	Day	12% 10% 27% 30% 17% 3	527
	11th to 20th	Day	8% 9% 32% 28% 17% 5%	517
	21st to end	Day	13% 10% 33% 26% 14% 4	583
September	1st to 10th	Day	16% 17% 22% 23% 17% 5%	530
	11th to 20th	Day	17% 10% 33% 21% 14% 4	530
	21st to end	Day	23% 23% 25% 19% 8% 2	530
October	1st to 10th	Day	21% 16% 26% 22% 12% 3	457
	11th to 20th	Day	18% 23% 27% 19% 10% 3	330
	21st to end	Day	26% 25% 24% 17% 7% 2	363
November	1st to 10th	Day	29% 26% 23% 14% 6% 1	330
	11th to 20th	Day	25% 24% 34% 14% 3	330
	21st to end	Day	23% 24% 25% 15% 9% 5%	220
December	1st to 10th	Day	21% 30% 30% 11% 6% 2	220
	11th to 20th	Day	31% 19% 28% 16% 5% 1	220
	21st to end	Day	20% 25% 24% 19% 8% 4	242
January	1st to 10th	Night	22% 25% 32% 16% 5%	1050
	11th to 20th	Night	18% 25% 36% 16% 4 1	950
	21st to end	Night	16% 30% 34% 15% 5% 1	924
February	1st to 10th	Night	18% 21% 31% 21% 7% 2	840
	11th to 20th	Night	17% 24% 30% 24% 6%	824
	21st to end	Night	17% 23% 29% 23% 7%	692
March	1st to 10th	Night	14% 21% 30% 25% 8% 1	840
	11th to 20th	Night	17% 19% 32% 25% 7% 1	840
	21st to end	Night	17% 19% 28% 25% 10% 1	924
April	1st to 10th	Night	16% 21% 27% 25% 10% 1	802
	11th to 20th	Night	17% 20% 28% 26% 9%	623
	21st to end	Night	17% 14% 33% 24% 11% 1	630
May	1st to 10th	Night	19% 15% 25% 27% 14%	603
	11th to 20th	Night	17% 9% 25% 32% 15% 1	414
	21st to end	Night	23% 9% 20% 30% 17% 1	455
June	1st to 10th	Night	20% 12% 26% 29% 11% 2	420
	11th to 20th	Night	21% 14% 28% 26% 10% 1	420
	21st to end	Night	9% 11% 31% 31% 17% 1	420
July	1st to 10th	Night	8% 6% 24% 38% 23%	390
	11th to 20th	Night	9% 5% 28% 44% 14% 1	388
	21st to end	Night	8% 5% 27% 39% 20% 1	438
August	1st to 10th	Night	10% 4 21% 41% 23% 1	417
	11th to 20th	Night	8% 6% 26% 38% 22% 1	594
	21st to end	Night	10% 8% 28% 38% 15% 1	660
September	1st to 10th	Night	12% 8% 24% 34% 18% 3	726
	11th to 20th	Night	16% 9% 25% 29% 18% 3	800
	21st to end	Night	16% 16% 31% 26% 10% 2	800
October	1st to 10th	Night	20% 11% 27% 27% 15% 1	800
	11th to 20th	Night	17% 18% 28% 27% 9% 1	800
	21st to end	Night	19% 23% 32% 19% 6% 1	880
November	1st to 10th	Night	24% 22% 30% 20% 4	873
	11th to 20th	Night	21% 28% 33% 14% 3 1	1050
	21st to end	Night	16% 29% 31% 18% 5% 1	1050
December	1st to 10th	Night	16% 28% 30% 18% 6% 1	1050
	11th to 20th	Night	17% 24% 35% 19% 5%	1050
	21st to end	Night	17% 24% 35% 16% 7% 1	1155

Page generated at 2026-06-28 00:10:44. Version ac07

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