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 2025-02-25.

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%	112080
	Night	5% 8% 3 7% 5% 4 5% 4 6% 8% 45%	115199
Transparency	Day	35% 6% 15% 27% 14% 3	111832
	Night	36% 6% 17% 26% 13% 2	115093
Seeing	Day	19% 18% 27% 22% 11% 3	15575
	Night	16% 19% 30% 24% 10% 1	24937

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 10% 5% 12% 6% 5% 4 4 6% 9% 37%	3179
	11th to 20th	Day	2 8% 7% 11% 7% 7% 5% 4 7% 9% 35%	3411
	21st to end	Day	1 6% 2 8% 4 4 4 3 6% 11% 50%	4004
February	1st to 10th	Day	3 9% 5% 11% 6% 6% 6% 3 7% 9% 34%	1639
	11th to 20th	Day	2 12% 4 10% 6% 4 5% 4 7% 9% 36%	1755
	21st to end	Day	2 10% 5% 11% 7% 4 4 3 7% 9% 38%	1598
March	1st to 10th	Day	1 7% 3 8% 5% 4 5% 5% 8% 11% 43%	3138
	11th to 20th	Day	3 10% 2 5% 3 3 4 3 7% 9% 51%	3458
	21st to end	Day	8% 16% 6% 11% 4 3 5% 4 6% 8% 30%	3855
April	1st to 10th	Day	5% 13% 4 8% 5% 4 5% 4 7% 10% 34%	2313
	11th to 20th	Day	8% 12% 3 9% 5% 4 5% 4 7% 7% 35%	2440
	21st to end	Day	10% 12% 3 7% 5% 4 4 5% 6% 9% 36%	2470
May	1st to 10th	Day	14% 16% 4 7% 4 4 4 4 5% 6% 30%	4156
	11th to 20th	Day	11% 7% 2 7% 6% 5% 6% 5% 8% 9% 34%	4654
	21st to end	Day	14% 7% 2 6% 5% 5% 5% 5% 7% 9% 35%	5161
June	1st to 10th	Day	12% 7% 3 7% 5% 5% 5% 4 6% 8% 37%	2850
	11th to 20th	Day	15% 7% 3 6% 5% 6% 6% 5% 7% 7% 32%	2850
	21st to end	Day	7% 4 2 5% 4 4 5% 5% 6% 8% 50%	2850
July	1st to 10th	Day	4 3 1 5% 4 4 4 3 6% 9% 57%	4740
	11th to 20th	Day	4 2 1 3 2 3 4 3 6% 8% 64%	4740
	21st to end	Day	2 2 1 3 2 3 3 3 5% 7% 70%	4868
August	1st to 10th	Day	10% 5% 2 5% 3 4 4 4 7% 8% 47%	4358
	11th to 20th	Day	5% 3 1 3 3 3 5% 4 6% 8% 59%	4028
	21st to end	Day	7% 3 1 3 2 3 3 3 5% 7% 61%	4521
September	1st to 10th	Day	11% 4 2 3 3 3 4 3 6% 7% 54%	2319
	11th to 20th	Day	10% 5% 2 5% 4 4 4 3 5% 8% 51%	2090
	21st to end	Day	10% 6% 1 4 3 4 3 3 5% 7% 54%	2090
October	1st to 10th	Day	7% 6% 2 4 3 3 4 3 5% 10% 53%	3369
	11th to 20th	Day	3 6% 2 5% 3 4 4 4 7% 10% 53%	2951
	21st to end	Day	6% 8% 3 6% 4 4 4 4 6% 8% 49%	3101
November	1st to 10th	Day	6% 11% 3 7% 3 4 4 4 7% 10% 41%	1694
	11th to 20th	Day	3 8% 3 6% 4 4 5% 4 7% 9% 48%	1600
	21st to end	Day	2 11% 5% 9% 7% 4 4 4 6% 9% 40%	1400
December	1st to 10th	Day	1 5% 3 5% 5% 3 4 4 6% 10% 53%	2290
	11th to 20th	Day	3 8% 3 9% 5% 4 5% 3 7% 10% 42%	2642
	21st to end	Day	2 8% 4 8% 6% 6% 4 4 6% 9% 44%	3498
January	1st to 10th	Night	3 10% 5% 13% 6% 4 4 4 7% 8% 36%	6766
	11th to 20th	Night	1 8% 4 11% 7% 6% 7% 5% 6% 9% 36%	6529
	21st to end	Night	1 6% 3 8% 4 5% 5% 4 7% 9% 46%	6952
February	1st to 10th	Night	3 12% 4 11% 6% 5% 5% 4 6% 9% 35%	2760
	11th to 20th	Night	2 13% 4 9% 4 5% 6% 4 6% 9% 37%	2532
	21st to end	Night	2 8% 4 11% 7% 6% 6% 4 5% 7% 40%	1947
March	1st to 10th	Night	1 6% 4 12% 7% 7% 7% 4 6% 7% 39%	3736
	11th to 20th	Night	3 7% 3 6% 4 4 5% 4 6% 8% 52%	3508
	21st to end	Night	7% 19% 7% 10% 4 4 3 4 5% 7% 28%	3784
April	1st to 10th	Night	9% 10% 3 7% 4 4 5% 4 6% 8% 40%	1866
	11th to 20th	Night	9% 10% 4 7% 4 4 4 5% 7% 8% 38%	1691
	21st to end	Night	7% 11% 4 7% 6% 4 4 3 7% 7% 40%	1710
May	1st to 10th	Night	15% 14% 4 8% 5% 4 4 3 5% 6% 32%	2810
	11th to 20th	Night	8% 6% 3 6% 3 5% 4 4 7% 10% 43%	2237
	21st to end	Night	15% 7% 3 7% 5% 5% 6% 5% 7% 7% 33%	2414
June	1st to 10th	Night	11% 6% 2 6% 5% 4 4 4 6% 9% 42%	1330
	11th to 20th	Night	17% 6% 2 5% 4 5% 4 4 6% 8% 39%	1330
	21st to end	Night	5% 3 2 5% 4 4 5% 4 6% 8% 56%	1330
July	1st to 10th	Night	3 3 1 3 3 3 5% 4 6% 9% 60%	2220
	11th to 20th	Night	4 2 1 3 3 2 2 3 5% 7% 68%	2220
	21st to end	Night	3 2 1 3 3 3 2 2 4 5% 72%	2667
August	1st to 10th	Night	11% 4 2 4 3 3 4 3 5% 7% 54%	2560
	11th to 20th	Night	5% 3 1 4 4 4 5% 4 8% 10% 52%	2811
	21st to end	Night	5% 2 1 3 3 3 3 4 6% 7% 62%	3146
September	1st to 10th	Night	10% 4 1 4 3 3 4 3 5% 6% 58%	1857
	11th to 20th	Night	11% 6% 2 4 2 2 3 3 5% 7% 54%	2090
	21st to end	Night	10% 6% 2 3 3 3 3 4 5% 7% 54%	2090
October	1st to 10th	Night	7% 5% 1 3 2 3 3 3 5% 8% 59%	3606
	11th to 20th	Night	3 4 1 3 3 3 3 3 7% 11% 57%	3962
	21st to end	Night	4 6% 3 7% 4 3 4 3 6% 7% 53%	4457
November	1st to 10th	Night	5% 12% 3 7% 5% 5% 4 4 7% 8% 41%	2585
	11th to 20th	Night	2 7% 3 7% 4 4 5% 5% 7% 9% 48%	2800
	21st to end	Night	3 10% 4 7% 5% 4 5% 3 6% 10% 42%	2998
December	1st to 10th	Night	2 6% 3 7% 5% 4 5% 5% 7% 10% 47%	4890
	11th to 20th	Night	2 9% 4 10% 6% 5% 6% 5% 8% 9% 36%	5550
	21st to end	Night	2 10% 5% 9% 5% 5% 5% 4 6% 8% 41%	7458

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	44% 7% 15% 23% 11% 1	3179
	11th to 20th	Day	46% 5% 17% 16% 13% 2	3434
	21st to end	Day	30% 6% 18% 34% 13%	4004
February	1st to 10th	Day	47% 6% 17% 20% 9% 2	1639
	11th to 20th	Day	43% 6% 19% 21% 9% 1	1764
	21st to end	Day	43% 7% 15% 22% 12% 1	1598
March	1st to 10th	Day	32% 9% 14% 27% 17% 1	3138
	11th to 20th	Day	29% 7% 22% 31% 10% 1	3459
	21st to end	Day	51% 8% 13% 22% 6%	3855
April	1st to 10th	Day	43% 7% 17% 23% 9% 1	2313
	11th to 20th	Day	45% 7% 15% 22% 10% 1	2440
	21st to end	Day	44% 7% 15% 21% 11% 1	2470
May	1st to 10th	Day	53% 4 11% 24% 7%	4156
	11th to 20th	Day	40% 10% 14% 26% 10% 1	4658
	21st to end	Day	42% 8% 15% 20% 14% 1	5162
June	1st to 10th	Day	43% 8% 14% 21% 12% 2	2850
	11th to 20th	Day	47% 6% 12% 20% 12% 2	2850
	21st to end	Day	30% 6% 16% 30% 14% 3	2850
July	1st to 10th	Day	25% 4 9% 30% 23% 9%	4666
	11th to 20th	Day	19% 4 8% 33% 25% 11%	4659
	21st to end	Day	15% 3 7% 28% 28% 19%	4714
August	1st to 10th	Day	34% 4 14% 25% 19% 5%	4341
	11th to 20th	Day	23% 3 19% 37% 15% 3	4067
	21st to end	Day	23% 4 10% 41% 20% 3	4520
September	1st to 10th	Day	29% 4 12% 28% 19% 8%	2319
	11th to 20th	Day	32% 6% 13% 29% 16% 4	2090
	21st to end	Day	30% 6% 14% 33% 14% 3	2090
October	1st to 10th	Day	28% 4 16% 37% 15% 1	3369
	11th to 20th	Day	28% 4 22% 29% 17% 1	2951
	21st to end	Day	34% 4 15% 31% 12% 4	3101
November	1st to 10th	Day	39% 9% 17% 23% 11%	1694
	11th to 20th	Day	32% 9% 22% 26% 10% 1	1600
	21st to end	Day	40% 8% 22% 19% 8% 3	1400
December	1st to 10th	Day	28% 6% 27% 29% 8% 2	2290
	11th to 20th	Day	36% 7% 26% 24% 6% 1	2644
	21st to end	Day	37% 5% 16% 25% 17% 1	3498
January	1st to 10th	Night	44% 8% 16% 24% 7% 1	6766
	11th to 20th	Night	45% 5% 16% 20% 11% 3	6568
	21st to end	Night	33% 7% 20% 28% 12% 1	6952
February	1st to 10th	Night	46% 7% 14% 18% 12% 2	2760
	11th to 20th	Night	43% 8% 18% 20% 10% 1	2533
	21st to end	Night	44% 6% 14% 25% 9% 2	1947
March	1st to 10th	Night	39% 10% 15% 22% 14% 1	3736
	11th to 20th	Night	28% 9% 25% 27% 10% 1	3508
	21st to end	Night	53% 8% 14% 19% 5%	3784
April	1st to 10th	Night	40% 8% 17% 25% 9% 1	1866
	11th to 20th	Night	41% 7% 14% 28% 9%	1691
	21st to end	Night	41% 7% 14% 28% 9% 1	1710
May	1st to 10th	Night	53% 5% 11% 24% 6%	2810
	11th to 20th	Night	32% 10% 12% 32% 15%	2237
	21st to end	Night	46% 8% 15% 20% 10%	2414
June	1st to 10th	Night	38% 6% 17% 27% 11% 1	1330
	11th to 20th	Night	43% 5% 16% 22% 13% 1	1330
	21st to end	Night	25% 5% 19% 31% 17% 3	1330
July	1st to 10th	Night	20% 4 16% 29% 23% 8%	2185
	11th to 20th	Night	16% 3 13% 31% 24% 13%	2178
	21st to end	Night	17% 2 8% 28% 28% 18%	2582
August	1st to 10th	Night	31% 3 15% 26% 17% 8%	2552
	11th to 20th	Night	27% 3 19% 33% 16% 2	2838
	21st to end	Night	21% 3 10% 40% 22% 3	3146
September	1st to 10th	Night	27% 5% 11% 31% 17% 8%	1857
	11th to 20th	Night	30% 4 15% 30% 17% 4	2090
	21st to end	Night	29% 5% 18% 30% 16% 3	2090
October	1st to 10th	Night	25% 3 13% 35% 22% 2	3606
	11th to 20th	Night	22% 4 23% 30% 19% 2	3962
	21st to end	Night	30% 5% 15% 38% 11% 1	4457
November	1st to 10th	Night	40% 6% 20% 22% 10% 1	2585
	11th to 20th	Night	32% 8% 23% 24% 12% 1	2800
	21st to end	Night	38% 7% 22% 20% 10% 3	2998
December	1st to 10th	Night	32% 6% 25% 24% 11% 2	4890
	11th to 20th	Night	43% 8% 23% 21% 6%	5547
	21st to end	Night	40% 5% 17% 22% 13% 3	7458

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	19% 22% 28% 18% 10% 4	200
	11th to 20th	Day	27% 17% 27% 21% 8% 2	200
	21st to end	Day	23% 33% 26% 9% 6% 2	220
February	1st to 10th	Day	25% 15% 32% 17% 9% 1	220
	11th to 20th	Day	19% 21% 27% 24% 8% 1	300
	21st to end	Day	21% 28% 28% 18% 4 1	386
March	1st to 10th	Day	20% 22% 29% 19% 7% 3	460
	11th to 20th	Day	18% 23% 25% 20% 12% 2	460
	21st to end	Day	24% 24% 27% 17% 7% 2	506
April	1st to 10th	Day	23% 25% 29% 17% 5%	460
	11th to 20th	Day	23% 23% 26% 17% 9% 2	452
	21st to end	Day	23% 24% 25% 19% 8% 1	460
May	1st to 10th	Day	19% 17% 28% 20% 12% 3	463
	11th to 20th	Day	25% 11% 24% 23% 14% 3	648
	21st to end	Day	26% 10% 22% 25% 14% 4	734
June	1st to 10th	Day	21% 18% 26% 23% 10% 2	680
	11th to 20th	Day	26% 19% 24% 20% 8% 3	680
	21st to end	Day	12% 12% 30% 27% 15% 4	680
July	1st to 10th	Day	11% 9% 28% 29% 19% 4	671
	11th to 20th	Day	11% 14% 26% 31% 15% 3	668
	21st to end	Day	8% 11% 32% 29% 16% 3	583
August	1st to 10th	Day	12% 10% 28% 31% 16% 3	487
	11th to 20th	Day	8% 9% 31% 29% 18% 5%	477
	21st to end	Day	14% 11% 34% 25% 13% 3	539
September	1st to 10th	Day	17% 18% 22% 22% 16% 4	490
	11th to 20th	Day	18% 11% 35% 21% 12% 3	490
	21st to end	Day	24% 23% 25% 18% 8% 2	490
October	1st to 10th	Day	22% 15% 26% 22% 12% 3	421
	11th to 20th	Day	18% 23% 27% 19% 11% 3	300
	21st to end	Day	26% 24% 24% 17% 7% 2	330
November	1st to 10th	Day	27% 26% 25% 15% 6% 1	300
	11th to 20th	Day	26% 24% 35% 12% 2	300
	21st to end	Day	23% 25% 24% 15% 10% 5%	200
December	1st to 10th	Day	20% 28% 32% 12% 7% 3	200
	11th to 20th	Day	28% 19% 30% 17% 6% 2	200
	21st to end	Day	21% 22% 22% 20% 9% 5%	220
January	1st to 10th	Night	21% 25% 32% 16% 5% 1	1000
	11th to 20th	Night	17% 25% 37% 16% 4 1	905
	21st to end	Night	15% 30% 34% 14% 5% 1	880
February	1st to 10th	Night	17% 21% 32% 22% 8% 2	800
	11th to 20th	Night	17% 24% 29% 24% 6%	784
	21st to end	Night	16% 22% 30% 24% 7%	646
March	1st to 10th	Night	13% 22% 31% 24% 9% 2	760
	11th to 20th	Night	16% 20% 30% 25% 7% 1	760
	21st to end	Night	17% 18% 26% 26% 11% 1	836
April	1st to 10th	Night	16% 22% 27% 24% 10% 1	726
	11th to 20th	Night	16% 21% 27% 26% 9%	563
	21st to end	Night	17% 15% 34% 24% 10% 1	570
May	1st to 10th	Night	19% 16% 25% 25% 15%	546
	11th to 20th	Night	16% 8% 26% 32% 17% 2	374
	21st to end	Night	24% 10% 19% 30% 16% 1	411
June	1st to 10th	Night	19% 12% 26% 29% 12% 2	380
	11th to 20th	Night	23% 15% 27% 24% 10% 1	380
	21st to end	Night	7% 12% 33% 29% 17% 1	380
July	1st to 10th	Night	8% 6% 24% 38% 23%	370
	11th to 20th	Night	9% 5% 29% 42% 14% 1	368
	21st to end	Night	6% 5% 28% 40% 20% 1	416
August	1st to 10th	Night	10% 4 21% 40% 24% 1	396
	11th to 20th	Night	8% 6% 26% 37% 22% 1	564
	21st to end	Night	10% 8% 29% 37% 15% 1	627
September	1st to 10th	Night	13% 9% 26% 33% 17% 3	689
	11th to 20th	Night	16% 10% 25% 28% 17% 3	760
	21st to end	Night	16% 16% 31% 26% 10% 2	760
October	1st to 10th	Night	20% 11% 26% 26% 15% 1	760
	11th to 20th	Night	16% 18% 28% 28% 9% 1	760
	21st to end	Night	18% 23% 32% 19% 6% 1	836
November	1st to 10th	Night	23% 22% 30% 20% 4	830
	11th to 20th	Night	22% 28% 33% 14% 3 1	1000
	21st to end	Night	16% 30% 31% 17% 5% 1	1000
December	1st to 10th	Night	15% 28% 30% 19% 6% 1	1000
	11th to 20th	Night	16% 24% 34% 20% 5%	1000
	21st to end	Night	18% 24% 34% 17% 7% 1	1100

Page generated at 2025-02-22 04:51:36. Version ac07

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