Jasper Marmot Meadows
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Jasper Marmot Meadows clear sky chart from 2005-11-06 to 2025-04-11.

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	7% 11% 4 11% 7% 6% 6% 5% 7% 8% 28%	116541
	Night	4 9% 4 11% 7% 7% 7% 5% 8% 9% 30%	120432
Transparency	Day	56% 8% 15% 14% 6% 1	116282
	Night	54% 9% 18% 14% 5% 1	120337
Seeing	Day	19% 13% 28% 25% 12% 3	16537
	Night	11% 10% 35% 31% 11% 1	25072

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	1 7% 7% 13% 9% 9% 8% 5% 9% 10% 22%	2719
	11th to 20th	Day	1 7% 4 15% 6% 5% 7% 7% 9% 8% 31%	3164
	21st to end	Day	1 11% 4 12% 8% 6% 7% 6% 8% 9% 28%	4004
February	1st to 10th	Day	2 8% 6% 15% 8% 7% 8% 5% 9% 8% 23%	1600
	11th to 20th	Day	1 9% 5% 16% 9% 7% 7% 6% 8% 8% 23%	1649
	21st to end	Day	1 7% 4 17% 12% 9% 7% 6% 7% 7% 23%	1635
March	1st to 10th	Day	6% 4 12% 9% 9% 10% 7% 10% 10% 24%	4518
	11th to 20th	Day	2 9% 5% 12% 7% 6% 7% 6% 8% 9% 29%	4657
	21st to end	Day	2 12% 6% 19% 10% 7% 6% 5% 6% 7% 20%	5969
April	1st to 10th	Day	3 15% 8% 17% 11% 9% 8% 5% 6% 6% 15%	2400
	11th to 20th	Day	4 15% 7% 17% 10% 6% 6% 5% 5% 6% 19%	2378
	21st to end	Day	6% 18% 5% 15% 8% 6% 5% 4 6% 7% 19%	2615
May	1st to 10th	Day	8% 20% 6% 11% 6% 5% 5% 3 6% 6% 22%	4420
	11th to 20th	Day	10% 15% 4 12% 7% 7% 6% 5% 7% 7% 21%	4582
	21st to end	Day	14% 21% 6% 14% 8% 6% 5% 4 5% 4 12%	5183
June	1st to 10th	Day	17% 13% 4 12% 7% 6% 6% 5% 6% 6% 18%	3040
	11th to 20th	Day	19% 17% 6% 11% 8% 6% 6% 5% 5% 5% 13%	3040
	21st to end	Day	12% 12% 5% 11% 8% 7% 6% 5% 6% 7% 21%	3040
July	1st to 10th	Day	10% 7% 3 7% 5% 4 5% 4 5% 6% 43%	5060
	11th to 20th	Day	8% 6% 2 6% 5% 5% 5% 4 6% 7% 46%	5038
	21st to end	Day	9% 7% 3 8% 6% 6% 7% 6% 7% 8% 33%	4825
August	1st to 10th	Day	12% 7% 3 6% 6% 5% 6% 4 6% 7% 38%	4401
	11th to 20th	Day	12% 7% 3 7% 5% 6% 6% 5% 7% 8% 33%	4330
	21st to end	Day	13% 8% 3 7% 5% 5% 6% 5% 7% 9% 32%	4466
September	1st to 10th	Day	10% 11% 4 10% 5% 6% 5% 4 5% 6% 33%	2280
	11th to 20th	Day	10% 10% 4 8% 5% 6% 5% 5% 6% 6% 34%	2218
	21st to end	Day	8% 12% 5% 11% 7% 6% 5% 4 6% 6% 29%	2090
October	1st to 10th	Day	5% 11% 4 8% 6% 5% 5% 5% 7% 9% 34%	3225
	11th to 20th	Day	6% 11% 3 8% 5% 6% 8% 6% 8% 9% 29%	2908
	21st to end	Day	2 9% 4 11% 6% 5% 6% 6% 6% 8% 36%	3101
November	1st to 10th	Day	3 12% 5% 15% 9% 8% 6% 5% 7% 7% 22%	1632
	11th to 20th	Day	2 7% 5% 10% 7% 7% 6% 7% 9% 11% 30%	1400
	21st to end	Day	1 11% 5% 12% 8% 8% 7% 5% 8% 10% 26%	1400
December	1st to 10th	Day	1 7% 4 11% 10% 7% 8% 6% 9% 9% 27%	2290
	11th to 20th	Day	1 8% 4 9% 7% 8% 9% 7% 9% 11% 27%	2272
	21st to end	Day	6% 4 9% 6% 5% 7% 6% 8% 12% 37%	2992
January	1st to 10th	Night	6% 5% 15% 10% 8% 8% 6% 8% 9% 24%	7226
	11th to 20th	Night	1 7% 3 11% 8% 7% 8% 6% 9% 10% 29%	6775
	21st to end	Night	1 10% 4 12% 7% 7% 7% 5% 8% 10% 30%	6952
February	1st to 10th	Night	2 10% 5% 13% 10% 8% 8% 6% 9% 8% 20%	2800
	11th to 20th	Night	1 9% 5% 12% 9% 8% 8% 5% 8% 9% 26%	2633
	21st to end	Night	1 9% 5% 12% 9% 8% 7% 6% 9% 9% 24%	1995
March	1st to 10th	Night	7% 4 11% 9% 8% 7% 6% 8% 9% 29%	5376
	11th to 20th	Night	2 7% 4 10% 8% 7% 8% 6% 10% 10% 27%	5326
	21st to end	Night	3 14% 6% 18% 8% 6% 5% 4 7% 9% 20%	5006
April	1st to 10th	Night	1 13% 5% 13% 9% 8% 7% 6% 8% 8% 22%	2000
	11th to 20th	Night	3 12% 5% 13% 8% 6% 6% 5% 7% 9% 28%	1758
	21st to end	Night	5% 12% 5% 12% 6% 5% 6% 6% 6% 8% 28%	1563
May	1st to 10th	Night	5% 16% 5% 11% 7% 5% 7% 5% 7% 7% 26%	2540
	11th to 20th	Night	7% 13% 4 12% 6% 7% 6% 4 6% 7% 27%	2309
	21st to end	Night	10% 16% 6% 12% 7% 7% 5% 5% 6% 7% 19%	2388
June	1st to 10th	Night	14% 11% 4 10% 4 7% 6% 4 6% 7% 28%	1140
	11th to 20th	Night	16% 14% 4 10% 8% 6% 6% 5% 6% 7% 19%	1140
	21st to end	Night	9% 6% 3 8% 6% 7% 7% 5% 8% 9% 31%	1140
July	1st to 10th	Night	11% 6% 1 4 3 4 4 3 6% 6% 52%	1900
	11th to 20th	Night	6% 4 1 5% 4 4 5% 4 6% 7% 54%	1922
	21st to end	Night	9% 6% 2 6% 4 5% 5% 4 7% 10% 43%	2724
August	1st to 10th	Night	12% 8% 2 6% 4 4 5% 5% 7% 9% 38%	2529
	11th to 20th	Night	13% 7% 2 6% 4 4 5% 5% 7% 10% 37%	2497
	21st to end	Night	12% 7% 3 6% 5% 5% 6% 5% 6% 8% 37%	3200
September	1st to 10th	Night	11% 8% 2 8% 5% 5% 5% 4 6% 8% 38%	1900
	11th to 20th	Night	9% 11% 3 8% 5% 5% 5% 4 6% 7% 37%	1962
	21st to end	Night	7% 9% 4 9% 5% 5% 6% 5% 7% 10% 33%	2090
October	1st to 10th	Night	4 10% 3 10% 6% 7% 6% 5% 7% 9% 34%	3753
	11th to 20th	Night	4 9% 3 7% 5% 5% 7% 6% 9% 11% 34%	4021
	21st to end	Night	3 8% 4 9% 6% 5% 6% 5% 8% 9% 38%	4457
November	1st to 10th	Night	3 13% 5% 12% 8% 8% 7% 5% 8% 7% 23%	2659
	11th to 20th	Night	1 9% 4 10% 7% 7% 8% 6% 9% 11% 28%	2982
	21st to end	Night	1 9% 5% 12% 8% 9% 7% 5% 8% 11% 25%	3000
December	1st to 10th	Night	2 7% 4 10% 7% 7% 7% 6% 9% 10% 29%	4890
	11th to 20th	Night	1 7% 4 11% 8% 8% 9% 6% 9% 11% 25%	5915
	21st to end	Night	6% 3 10% 7% 7% 7% 6% 9% 11% 33%	7964

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	61% 10% 17% 9% 3	2719
	11th to 20th	Day	52% 8% 13% 13% 12% 2	3185
	21st to end	Day	54% 11% 23% 10% 3	4004
February	1st to 10th	Day	57% 9% 13% 9% 11% 2	1600
	11th to 20th	Day	59% 8% 13% 14% 6%	1657
	21st to end	Day	59% 8% 13% 13% 6% 1	1635
March	1st to 10th	Day	55% 10% 15% 13% 8%	4518
	11th to 20th	Day	54% 6% 16% 18% 5%	4657
	21st to end	Day	66% 6% 12% 10% 7%	5969
April	1st to 10th	Day	71% 7% 14% 8% 2	2400
	11th to 20th	Day	64% 7% 15% 11% 2	2378
	21st to end	Day	64% 9% 13% 11% 2	2615
May	1st to 10th	Day	62% 7% 14% 13% 4	4420
	11th to 20th	Day	59% 7% 16% 13% 5%	4586
	21st to end	Day	72% 8% 10% 7% 3	5184
June	1st to 10th	Day	65% 7% 11% 11% 4 2	3040
	11th to 20th	Day	72% 7% 10% 8% 3	3040
	21st to end	Day	61% 8% 13% 11% 5% 1	3040
July	1st to 10th	Day	43% 7% 9% 18% 15% 7%	4981
	11th to 20th	Day	39% 6% 12% 22% 18% 2	4951
	21st to end	Day	53% 6% 11% 14% 11% 4	4672
August	1st to 10th	Day	43% 8% 12% 27% 10%	4384
	11th to 20th	Day	48% 9% 17% 20% 6% 1	4372
	21st to end	Day	54% 7% 13% 21% 4	4465
September	1st to 10th	Day	53% 5% 15% 21% 5% 1	2280
	11th to 20th	Day	50% 7% 17% 17% 8%	2218
	21st to end	Day	57% 8% 14% 14% 6% 1	2090
October	1st to 10th	Day	56% 9% 18% 13% 3	3225
	11th to 20th	Day	59% 8% 17% 15% 1	2908
	21st to end	Day	56% 7% 21% 13% 3	3101
November	1st to 10th	Day	61% 10% 15% 10% 4 1	1632
	11th to 20th	Day	50% 13% 21% 11% 5% 1	1400
	21st to end	Day	55% 12% 18% 9% 5% 2	1400
December	1st to 10th	Day	59% 14% 14% 8% 3 1	2290
	11th to 20th	Day	56% 11% 18% 11% 4 1	2274
	21st to end	Day	48% 9% 22% 15% 6%	2992
January	1st to 10th	Night	60% 9% 17% 11% 3	7226
	11th to 20th	Night	52% 9% 11% 13% 14% 1	6816
	21st to end	Night	57% 10% 18% 12% 3	6952
February	1st to 10th	Night	61% 8% 13% 9% 8% 2	2800
	11th to 20th	Night	55% 9% 17% 13% 6% 1	2635
	21st to end	Night	54% 7% 15% 17% 7% 1	1995
March	1st to 10th	Night	51% 11% 16% 14% 7%	5376
	11th to 20th	Night	55% 6% 20% 15% 4	5327
	21st to end	Night	62% 9% 13% 11% 5%	5006
April	1st to 10th	Night	60% 9% 18% 11% 2	2000
	11th to 20th	Night	52% 9% 19% 16% 4	1758
	21st to end	Night	52% 11% 15% 17% 4	1563
May	1st to 10th	Night	54% 10% 18% 17% 2	2540
	11th to 20th	Night	53% 10% 17% 14% 7%	2309
	21st to end	Night	63% 11% 14% 10% 2	2388
June	1st to 10th	Night	54% 7% 17% 14% 6% 1	1140
	11th to 20th	Night	62% 8% 16% 10% 3	1140
	21st to end	Night	46% 10% 21% 17% 5% 1	1140
July	1st to 10th	Night	34% 8% 13% 23% 21% 2	1870
	11th to 20th	Night	30% 6% 15% 28% 20% 1	1886
	21st to end	Night	41% 8% 16% 21% 9% 6%	2638
August	1st to 10th	Night	42% 9% 19% 28% 3	2521
	11th to 20th	Night	43% 11% 22% 19% 5%	2521
	21st to end	Night	46% 9% 23% 18% 4	3200
September	1st to 10th	Night	43% 7% 20% 22% 7% 1	1900
	11th to 20th	Night	46% 7% 20% 19% 8% 1	1962
	21st to end	Night	47% 11% 20% 17% 5% 1	2090
October	1st to 10th	Night	56% 10% 19% 12% 2	3753
	11th to 20th	Night	52% 9% 23% 13% 3	4021
	21st to end	Night	55% 8% 23% 11% 3	4457
November	1st to 10th	Night	61% 10% 17% 10% 3	2659
	11th to 20th	Night	52% 13% 19% 10% 5%	2982
	21st to end	Night	55% 12% 17% 10% 5% 1	3000
December	1st to 10th	Night	58% 11% 17% 10% 4	4890
	11th to 20th	Night	60% 13% 15% 8% 3	5912
	21st to end	Night	53% 9% 20% 15% 3	7964

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	8% 6% 19% 47% 17% 4	200
	11th to 20th	Day	10% 6% 26% 40% 15% 4	200
	21st to end	Day	16% 6% 32% 31% 11% 4	220
February	1st to 10th	Day	16% 10% 29% 29% 13% 5%	200
	11th to 20th	Day	15% 12% 28% 27% 15% 4	289
	21st to end	Day	11% 19% 38% 19% 11% 2	407
March	1st to 10th	Day	13% 23% 31% 19% 11% 3	500
	11th to 20th	Day	14% 21% 33% 20% 10% 3	500
	21st to end	Day	16% 20% 29% 21% 9% 5%	550
April	1st to 10th	Day	19% 20% 30% 22% 7% 1	500
	11th to 20th	Day	17% 15% 31% 23% 10% 5%	453
	21st to end	Day	20% 18% 25% 22% 10% 4	460
May	1st to 10th	Day	24% 13% 29% 22% 10% 2	463
	11th to 20th	Day	18% 11% 24% 29% 14% 3	602
	21st to end	Day	23% 10% 21% 24% 19% 3	743
June	1st to 10th	Day	25% 13% 30% 22% 9% 1	870
	11th to 20th	Day	29% 13% 26% 22% 9% 2	870
	21st to end	Day	19% 12% 24% 25% 15% 4	870
July	1st to 10th	Day	20% 10% 27% 29% 12% 2	856
	11th to 20th	Day	19% 11% 28% 27% 12% 3	843
	21st to end	Day	16% 13% 26% 25% 16% 4	553
August	1st to 10th	Day	18% 9% 25% 27% 16% 5%	487
	11th to 20th	Day	16% 14% 33% 22% 12% 4	477
	21st to end	Day	21% 12% 30% 22% 12% 3	539
September	1st to 10th	Day	25% 14% 27% 19% 13% 3	490
	11th to 20th	Day	18% 14% 27% 26% 13% 3	490
	21st to end	Day	27% 21% 26% 15% 8% 2	490
October	1st to 10th	Day	21% 16% 29% 19% 10% 5%	490
	11th to 20th	Day	20% 16% 27% 22% 12% 3	340
	21st to end	Day	18% 9% 28% 35% 7% 2	330
November	1st to 10th	Day	19% 14% 32% 26% 7% 3	235
	11th to 20th	Day	15% 12% 31% 29% 10% 5%	200
	21st to end	Day	16% 13% 25% 30% 11% 6%	200
December	1st to 10th	Day	11% 6% 26% 33% 18% 7%	200
	11th to 20th	Day	9% 6% 24% 41% 15% 6%	200
	21st to end	Day	8% 7% 21% 39% 17% 8%	220
January	1st to 10th	Night	9% 13% 38% 33% 7% 1	1100
	11th to 20th	Night	7% 14% 42% 28% 7% 2	948
	21st to end	Night	9% 14% 44% 24% 7% 1	880
February	1st to 10th	Night	11% 11% 37% 29% 12% 1	800
	11th to 20th	Night	8% 10% 38% 35% 8% 1	784
	21st to end	Night	8% 11% 40% 28% 10% 3	660
March	1st to 10th	Night	6% 12% 42% 28% 11% 2	800
	11th to 20th	Night	5% 12% 43% 29% 10% 1	800
	21st to end	Night	7% 12% 35% 32% 12% 2	880
April	1st to 10th	Night	8% 12% 31% 35% 12% 1	800
	11th to 20th	Night	9% 12% 34% 30% 14% 1	628
	21st to end	Night	15% 8% 31% 33% 13%	423
May	1st to 10th	Night	14% 6% 23% 45% 13%	380
	11th to 20th	Night	11% 3 28% 41% 16% 1	374
	21st to end	Night	20% 5% 23% 29% 21% 1	411
June	1st to 10th	Night	20% 3 31% 31% 13% 1	380
	11th to 20th	Night	22% 6% 23% 33% 14% 2	380
	21st to end	Night	15% 6% 23% 34% 21% 2	380
July	1st to 10th	Night	16% 5% 19% 41% 18% 1	370
	11th to 20th	Night	16% 6% 21% 33% 22% 1	368
	21st to end	Night	12% 3 19% 43% 22%	416
August	1st to 10th	Night	16% 2 15% 39% 28% 2	378
	11th to 20th	Night	15% 4 20% 38% 21% 2	376
	21st to end	Night	17% 6% 25% 39% 12% 1	655
September	1st to 10th	Night	17% 6% 24% 37% 15% 1	760
	11th to 20th	Night	17% 5% 25% 33% 18% 1	760
	21st to end	Night	18% 12% 32% 27% 11% 1	760
October	1st to 10th	Night	15% 10% 31% 34% 9% 1	760
	11th to 20th	Night	13% 11% 38% 29% 8% 1	760
	21st to end	Night	13% 12% 41% 27% 7%	836
November	1st to 10th	Night	12% 12% 41% 28% 5% 1	780
	11th to 20th	Night	10% 16% 41% 27% 4 1	982
	21st to end	Night	9% 12% 45% 26% 7% 1	1000
December	1st to 10th	Night	9% 12% 42% 28% 9% 1	1000
	11th to 20th	Night	8% 10% 44% 29% 8% 1	1093
	21st to end	Night	5% 10% 43% 30% 10% 2	1210

Page generated at 2025-04-08 07:17:25. Version ac07

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