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 2026-08-15.

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	7% 10% 4 10% 7% 6% 6% 5% 7% 9% 30%	148456
	Night	4 8% 4 10% 7% 6% 7% 5% 8% 9% 32%	142112
Transparency	Day	54% 8% 16% 15% 6% 1	148156
	Night	52% 9% 18% 14% 5% 1	141995
Seeing	Day	19% 14% 28% 24% 12% 3	18501
	Night	11% 10% 35% 32% 11% 1	26639

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 6% 6% 12% 8% 8% 8% 6% 11% 12% 24%	3527
	11th to 20th	Day	1 5% 3 12% 5% 5% 6% 6% 9% 9% 41%	4138
	21st to end	Day	1 9% 4 10% 7% 6% 8% 6% 9% 11% 29%	5186
February	1st to 10th	Day	2 8% 6% 15% 8% 7% 8% 5% 9% 8% 24%	1680
	11th to 20th	Day	1 9% 5% 16% 9% 7% 7% 6% 8% 8% 23%	1734
	21st to end	Day	1 7% 4 16% 12% 9% 7% 6% 8% 8% 22%	1714
March	1st to 10th	Day	6% 4 12% 9% 9% 10% 7% 10% 10% 24%	4618
	11th to 20th	Day	2 9% 5% 12% 7% 6% 7% 6% 8% 9% 29%	4759
	21st to end	Day	2 12% 6% 19% 10% 7% 6% 5% 7% 7% 20%	6101
April	1st to 10th	Day	3 15% 7% 16% 11% 8% 8% 5% 6% 5% 15%	2520
	11th to 20th	Day	3 14% 6% 17% 10% 6% 6% 5% 6% 7% 20%	2630
	21st to end	Day	5% 16% 5% 14% 8% 6% 5% 4 6% 8% 22%	2891
May	1st to 10th	Day	6% 14% 4 8% 5% 5% 5% 4 7% 8% 36%	8195
	11th to 20th	Day	9% 12% 3 10% 6% 6% 6% 5% 8% 10% 23%	8533
	21st to end	Day	13% 15% 4 10% 6% 5% 5% 4 6% 7% 25%	9685
June	1st to 10th	Day	17% 13% 4 11% 7% 6% 6% 5% 6% 7% 20%	3360
	11th to 20th	Day	18% 16% 5% 11% 8% 6% 6% 5% 5% 6% 14%	3360
	21st to end	Day	13% 12% 5% 11% 8% 7% 6% 5% 6% 7% 21%	3360
July	1st to 10th	Day	8% 6% 2 6% 5% 5% 6% 5% 7% 9% 41%	9420
	11th to 20th	Day	10% 6% 2 6% 5% 5% 5% 5% 7% 8% 41%	9384
	21st to end	Day	6% 7% 2 6% 5% 6% 7% 6% 9% 10% 37%	8979
August	1st to 10th	Day	12% 7% 3 6% 6% 5% 6% 4 6% 8% 38%	4681
	11th to 20th	Day	12% 7% 3 7% 5% 6% 6% 5% 7% 8% 33%	4527
	21st to end	Day	13% 8% 3 7% 5% 5% 6% 5% 7% 9% 34%	4607
September	1st to 10th	Day	10% 11% 4 9% 5% 6% 5% 4 5% 6% 35%	2400
	11th to 20th	Day	10% 10% 3 8% 5% 6% 5% 5% 7% 7% 35%	2335
	21st to end	Day	9% 12% 5% 11% 7% 6% 6% 4 6% 6% 29%	2200
October	1st to 10th	Day	5% 11% 4 8% 6% 5% 5% 5% 7% 9% 34%	3327
	11th to 20th	Day	6% 11% 3 8% 5% 7% 8% 6% 8% 9% 29%	3000
	21st to end	Day	2 9% 4 11% 6% 5% 6% 5% 6% 8% 37%	3200
November	1st to 10th	Day	3 12% 5% 14% 8% 8% 6% 5% 8% 8% 23%	1715
	11th to 20th	Day	2 7% 5% 10% 7% 7% 6% 7% 9% 11% 30%	1470
	21st to end	Day	1 11% 5% 12% 8% 8% 7% 5% 8% 10% 26%	1470
December	1st to 10th	Day	2 7% 4 11% 9% 7% 8% 6% 9% 9% 27%	2360
	11th to 20th	Day	1 8% 4 9% 7% 8% 9% 7% 10% 11% 27%	2332
	21st to end	Day	6% 4 9% 6% 5% 7% 6% 8% 12% 37%	3058
January	1st to 10th	Night	5% 5% 14% 9% 9% 9% 7% 9% 10% 24%	9366
	11th to 20th	Night	1 6% 3 9% 7% 6% 7% 6% 9% 9% 37%	8815
	21st to end	Night	1 9% 4 11% 6% 7% 6% 5% 8% 10% 32%	8994
February	1st to 10th	Night	2 10% 5% 12% 10% 8% 8% 6% 9% 8% 21%	2940
	11th to 20th	Night	1 9% 4 13% 9% 8% 8% 5% 8% 10% 26%	2768
	21st to end	Night	1 9% 5% 12% 9% 8% 8% 6% 9% 10% 23%	2092
March	1st to 10th	Night	7% 4 11% 9% 8% 7% 6% 9% 10% 29%	5496
	11th to 20th	Night	2 7% 4 10% 8% 7% 8% 7% 10% 10% 27%	5444
	21st to end	Night	3 14% 6% 18% 7% 6% 5% 4 7% 9% 20%	5116
April	1st to 10th	Night	1 13% 5% 13% 9% 8% 7% 6% 8% 8% 22%	2100
	11th to 20th	Night	3 11% 5% 13% 7% 6% 5% 5% 7% 9% 29%	1940
	21st to end	Night	5% 11% 5% 12% 5% 4 7% 6% 6% 8% 30%	1727
May	1st to 10th	Night	5% 12% 3 7% 5% 4 5% 4 6% 9% 39%	4724
	11th to 20th	Night	7% 11% 3 10% 6% 7% 7% 5% 7% 10% 27%	4325
	21st to end	Night	8% 11% 4 7% 5% 5% 5% 5% 6% 9% 36%	4468
June	1st to 10th	Night	13% 10% 4 9% 4 7% 5% 5% 7% 7% 29%	1260
	11th to 20th	Night	16% 13% 3 10% 8% 6% 6% 5% 6% 7% 21%	1260
	21st to end	Night	10% 7% 3 8% 6% 7% 7% 5% 8% 9% 31%	1260
July	1st to 10th	Night	8% 5% 1 4 3 4 4 4 8% 9% 49%	3540
	11th to 20th	Night	10% 4 1 5% 4 4 6% 4 7% 8% 46%	3576
	21st to end	Night	9% 5% 1 4 3 4 5% 4 7% 10% 46%	5086
August	1st to 10th	Night	11% 7% 2 6% 4 4 6% 5% 7% 9% 39%	2689
	11th to 20th	Night	13% 7% 2 6% 4 4 5% 5% 7% 9% 37%	2609
	21st to end	Night	12% 7% 3 6% 4 4 6% 5% 6% 8% 38%	3301
September	1st to 10th	Night	10% 8% 2 7% 5% 5% 5% 4 6% 8% 40%	2000
	11th to 20th	Night	9% 10% 3 8% 5% 5% 5% 4 6% 7% 39%	2065
	21st to end	Night	7% 9% 4 9% 5% 5% 6% 5% 7% 9% 34%	2200
October	1st to 10th	Night	4 10% 3 10% 6% 7% 6% 5% 7% 9% 34%	3871
	11th to 20th	Night	4 9% 3 7% 5% 5% 6% 6% 9% 10% 35%	4149
	21st to end	Night	3 8% 3 8% 6% 5% 6% 5% 8% 9% 38%	4600
November	1st to 10th	Night	3 12% 5% 12% 8% 8% 7% 6% 8% 8% 24%	2796
	11th to 20th	Night	1 9% 4 10% 7% 7% 8% 6% 9% 11% 29%	3131
	21st to end	Night	1 9% 5% 12% 8% 8% 7% 5% 9% 11% 26%	3150
December	1st to 10th	Night	2 7% 4 10% 7% 7% 8% 6% 9% 11% 29%	5040
	11th to 20th	Night	1 7% 5% 11% 8% 8% 9% 6% 10% 11% 25%	6074
	21st to end	Night	6% 3 10% 7% 7% 7% 6% 9% 11% 33%	8140

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% 11% 17% 8% 3	3527
	11th to 20th	Day	47% 8% 17% 17% 10% 2	4159
	21st to end	Day	52% 11% 22% 12% 3	5187
February	1st to 10th	Day	56% 9% 13% 10% 10% 2	1680
	11th to 20th	Day	60% 7% 13% 14% 6%	1742
	21st to end	Day	60% 8% 13% 13% 5% 1	1714
March	1st to 10th	Day	55% 10% 15% 13% 7%	4618
	11th to 20th	Day	55% 6% 16% 17% 5%	4759
	21st to end	Day	66% 6% 12% 10% 7%	6101
April	1st to 10th	Day	71% 7% 13% 8% 1	2520
	11th to 20th	Day	63% 7% 16% 11% 2	2630
	21st to end	Day	62% 9% 14% 13% 3	2891
May	1st to 10th	Day	48% 7% 21% 19% 5%	8195
	11th to 20th	Day	60% 8% 16% 13% 4	8537
	21st to end	Day	59% 9% 18% 12% 2	9686
June	1st to 10th	Day	64% 7% 11% 11% 5% 2	3360
	11th to 20th	Day	70% 7% 11% 9% 4	3360
	21st to end	Day	61% 8% 13% 12% 4 1	3360
July	1st to 10th	Day	43% 7% 13% 20% 12% 4	9341
	11th to 20th	Day	43% 6% 11% 21% 17% 2	9297
	21st to end	Day	45% 8% 16% 19% 11% 2	8784
August	1st to 10th	Day	44% 8% 13% 26% 10%	4664
	11th to 20th	Day	48% 9% 17% 20% 5%	4569
	21st to end	Day	52% 7% 13% 21% 6% 1	4606
September	1st to 10th	Day	51% 6% 15% 21% 5% 1	2400
	11th to 20th	Day	49% 7% 17% 19% 8%	2335
	21st to end	Day	56% 8% 15% 13% 6% 1	2200
October	1st to 10th	Day	57% 9% 18% 13% 3	3327
	11th to 20th	Day	59% 8% 16% 15% 2	3000
	21st to end	Day	56% 7% 21% 13% 3	3200
November	1st to 10th	Day	61% 9% 15% 10% 3 1	1715
	11th to 20th	Day	50% 12% 21% 11% 5% 1	1470
	21st to end	Day	55% 11% 18% 9% 5% 2	1470
December	1st to 10th	Day	60% 14% 14% 8% 3 1	2360
	11th to 20th	Day	57% 11% 18% 11% 4 1	2334
	21st to end	Day	48% 9% 22% 15% 6%	3058
January	1st to 10th	Night	63% 9% 16% 9% 3	9367
	11th to 20th	Night	47% 8% 16% 15% 13% 1	8856
	21st to end	Night	56% 11% 17% 14% 2	8994
February	1st to 10th	Night	61% 9% 13% 9% 8% 1	2940
	11th to 20th	Night	55% 9% 17% 12% 6% 1	2770
	21st to end	Night	56% 7% 14% 16% 6% 1	2092
March	1st to 10th	Night	51% 11% 16% 14% 7%	5496
	11th to 20th	Night	55% 6% 20% 14% 4	5445
	21st to end	Night	62% 9% 13% 11% 5%	5116
April	1st to 10th	Night	59% 9% 19% 11% 2	2100
	11th to 20th	Night	51% 9% 20% 15% 5%	1940
	21st to end	Night	52% 10% 15% 18% 4	1727
May	1st to 10th	Night	42% 8% 30% 18% 2	4721
	11th to 20th	Night	55% 9% 15% 16% 5%	4325
	21st to end	Night	48% 10% 25% 14% 3	4472
June	1st to 10th	Night	54% 7% 17% 14% 7% 2	1260
	11th to 20th	Night	61% 8% 16% 12% 3	1260
	21st to end	Night	47% 10% 21% 17% 5% 1	1260
July	1st to 10th	Night	36% 6% 19% 23% 13% 2	3510
	11th to 20th	Night	39% 6% 12% 25% 16% 1	3540
	21st to end	Night	36% 8% 21% 24% 7% 3	4976
August	1st to 10th	Night	42% 9% 19% 28% 3	2681
	11th to 20th	Night	44% 11% 22% 19% 4	2633
	21st to end	Night	45% 9% 22% 19% 5%	3301
September	1st to 10th	Night	42% 7% 21% 22% 7% 1	2000
	11th to 20th	Night	45% 7% 21% 20% 8%	2065
	21st to end	Night	46% 11% 21% 16% 5% 1	2200
October	1st to 10th	Night	56% 10% 19% 12% 2	3871
	11th to 20th	Night	52% 9% 22% 14% 3	4149
	21st to end	Night	55% 8% 24% 11% 3	4600
November	1st to 10th	Night	61% 9% 17% 10% 3	2796
	11th to 20th	Night	53% 13% 19% 10% 5%	3131
	21st to end	Night	55% 11% 17% 11% 4 1	3150
December	1st to 10th	Night	58% 11% 17% 9% 4	5040
	11th to 20th	Night	61% 13% 15% 8% 3	6071
	21st to end	Night	53% 9% 20% 14% 3	8140

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	9% 8% 20% 45% 15% 4	220
	11th to 20th	Day	10% 7% 25% 41% 14% 3	220
	21st to end	Day	15% 5% 33% 33% 10% 4	242
February	1st to 10th	Day	16% 10% 30% 28% 11% 4	220
	11th to 20th	Day	14% 12% 29% 27% 14% 4	314
	21st to end	Day	13% 20% 37% 19% 10% 2	438
March	1st to 10th	Day	15% 23% 30% 19% 10% 3	540
	11th to 20th	Day	15% 22% 32% 19% 9% 3	540
	21st to end	Day	16% 21% 28% 20% 9% 5%	594
April	1st to 10th	Day	18% 20% 31% 22% 7% 1	540
	11th to 20th	Day	16% 17% 31% 22% 10% 4	532
	21st to end	Day	18% 19% 27% 21% 11% 4	540
May	1st to 10th	Day	23% 14% 29% 22% 10% 2	543
	11th to 20th	Day	19% 12% 24% 29% 14% 3	694
	21st to end	Day	23% 12% 21% 23% 17% 4	854
June	1st to 10th	Day	25% 14% 30% 22% 9% 1	990
	11th to 20th	Day	27% 14% 25% 23% 9% 2	990
	21st to end	Day	19% 12% 24% 25% 15% 4	990
July	1st to 10th	Day	19% 12% 27% 27% 12% 2	976
	11th to 20th	Day	20% 12% 28% 26% 12% 2	962
	21st to end	Day	15% 14% 26% 24% 16% 4	643
August	1st to 10th	Day	18% 10% 24% 28% 15% 5%	567
	11th to 20th	Day	16% 15% 33% 21% 11% 4	534
	21st to end	Day	19% 11% 29% 22% 14% 4	583
September	1st to 10th	Day	23% 13% 27% 19% 14% 4	530
	11th to 20th	Day	17% 13% 26% 27% 13% 4	530
	21st to end	Day	27% 23% 26% 15% 8% 2	530
October	1st to 10th	Day	21% 17% 28% 19% 10% 5%	530
	11th to 20th	Day	19% 16% 27% 22% 13% 3	372
	21st to end	Day	18% 12% 28% 34% 7% 2	363
November	1st to 10th	Day	19% 14% 33% 24% 7% 3	258
	11th to 20th	Day	15% 13% 30% 28% 10% 4	220
	21st to end	Day	15% 13% 24% 30% 12% 6%	220
December	1st to 10th	Day	11% 8% 26% 32% 16% 6%	220
	11th to 20th	Day	11% 8% 25% 37% 14% 5%	220
	21st to end	Day	7% 8% 22% 40% 15% 7%	242
January	1st to 10th	Night	8% 13% 39% 32% 6% 1	1160
	11th to 20th	Night	7% 15% 41% 28% 7% 2	998
	21st to end	Night	9% 14% 44% 25% 7% 1	924
February	1st to 10th	Night	11% 11% 37% 29% 11% 1	840
	11th to 20th	Night	7% 10% 38% 36% 8% 1	824
	21st to end	Night	8% 12% 39% 28% 10% 3	692
March	1st to 10th	Night	6% 12% 42% 27% 10% 2	840
	11th to 20th	Night	5% 13% 43% 28% 10% 1	840
	21st to end	Night	7% 12% 36% 31% 12% 2	924
April	1st to 10th	Night	8% 12% 31% 36% 12% 1	840
	11th to 20th	Night	9% 12% 34% 31% 13% 1	692
	21st to end	Night	13% 7% 30% 36% 13%	467
May	1st to 10th	Night	13% 5% 24% 46% 12%	420
	11th to 20th	Night	11% 4 27% 40% 16% 1	414
	21st to end	Night	19% 6% 24% 30% 20% 1	455
June	1st to 10th	Night	19% 4 30% 33% 13% 1	420
	11th to 20th	Night	21% 6% 22% 34% 15% 1	420
	21st to end	Night	15% 6% 22% 35% 20% 2	420
July	1st to 10th	Night	15% 5% 20% 42% 17% 1	410
	11th to 20th	Night	16% 6% 22% 35% 20% 1	408
	21st to end	Night	11% 3 19% 44% 22% 1	460
August	1st to 10th	Night	15% 1 15% 38% 29% 2	418
	11th to 20th	Night	15% 4 20% 39% 20% 2	404
	21st to end	Night	16% 6% 24% 39% 14% 1	690
September	1st to 10th	Night	16% 6% 24% 37% 16% 1	800
	11th to 20th	Night	16% 5% 24% 34% 19% 2	800
	21st to end	Night	17% 13% 32% 27% 11% 1	800
October	1st to 10th	Night	15% 10% 31% 35% 9% 1	800
	11th to 20th	Night	13% 12% 38% 29% 9% 1	800
	21st to end	Night	12% 13% 41% 26% 6%	880
November	1st to 10th	Night	11% 13% 42% 28% 5% 1	820
	11th to 20th	Night	10% 16% 42% 27% 4 1	1031
	21st to end	Night	9% 12% 45% 26% 7% 1	1050
December	1st to 10th	Night	8% 12% 42% 28% 8% 1	1050
	11th to 20th	Night	8% 11% 44% 28% 8% 1	1152
	21st to end	Night	5% 10% 44% 30% 10% 1	1276

Page generated at 2026-08-12 01:37:19. Version ac07

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