Hinton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hinton clear sky chart from 2005-11-06 to 2026-04-02.

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% 10% 4 10% 6% 5% 5% 4 6% 8% 31%	134941
	Night	7% 11% 4 10% 6% 5% 5% 4 6% 7% 32%	135574
Transparency	Day	48% 9% 15% 18% 9% 1	134635
	Night	48% 8% 16% 19% 9% 1	135459
Seeing	Day	19% 16% 29% 23% 11% 3	17931
	Night	15% 13% 31% 28% 12% 1	26416

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 11% 6% 13% 8% 7% 6% 5% 6% 8% 27%	3527
	11th to 20th	Day	2 8% 4 11% 7% 5% 5% 5% 9% 6% 38%	3924
	21st to end	Day	3 10% 5% 12% 7% 6% 7% 5% 6% 9% 30%	5186
February	1st to 10th	Day	4 12% 6% 14% 6% 6% 6% 5% 7% 7% 26%	1680
	11th to 20th	Day	4 14% 6% 12% 9% 6% 6% 4 6% 7% 26%	1699
	21st to end	Day	2 12% 6% 15% 9% 8% 5% 5% 5% 7% 26%	1721
March	1st to 10th	Day	3 9% 5% 13% 8% 7% 6% 4 7% 9% 30%	4618
	11th to 20th	Day	4 11% 5% 7% 5% 5% 5% 5% 7% 9% 37%	4764
	21st to end	Day	7% 16% 6% 17% 6% 5% 5% 4 6% 7% 22%	6090
April	1st to 10th	Day	6% 15% 5% 11% 9% 6% 7% 6% 8% 7% 19%	2413
	11th to 20th	Day	6% 18% 5% 10% 7% 6% 5% 5% 6% 6% 25%	2530
	21st to end	Day	10% 16% 5% 10% 7% 6% 5% 4 6% 7% 26%	2748
May	1st to 10th	Day	10% 14% 4 10% 5% 6% 5% 4 5% 6% 31%	6320
	11th to 20th	Day	13% 12% 4 11% 7% 7% 7% 5% 6% 8% 20%	6683
	21st to end	Day	14% 11% 4 10% 6% 5% 5% 4 6% 7% 27%	7485
June	1st to 10th	Day	20% 10% 3 8% 6% 5% 6% 4 7% 7% 25%	3200
	11th to 20th	Day	21% 11% 4 10% 7% 6% 5% 5% 5% 6% 20%	3200
	21st to end	Day	13% 9% 3 10% 7% 7% 5% 5% 7% 7% 28%	3200
July	1st to 10th	Day	13% 6% 2 7% 5% 5% 6% 5% 7% 9% 36%	7240
	11th to 20th	Day	14% 6% 2 7% 5% 5% 6% 4 6% 7% 38%	7240
	21st to end	Day	13% 7% 2 7% 5% 5% 6% 5% 7% 9% 33%	7063
August	1st to 10th	Day	16% 5% 2 5% 4 4 5% 4 6% 7% 42%	4541
	11th to 20th	Day	13% 7% 3 8% 5% 5% 6% 4 7% 8% 34%	4470
	21st to end	Day	15% 8% 2 7% 5% 4 5% 4 5% 7% 38%	4648
September	1st to 10th	Day	14% 8% 2 7% 5% 5% 5% 4 6% 8% 38%	2400
	11th to 20th	Day	13% 9% 3 6% 4 4 5% 4 6% 7% 39%	2321
	21st to end	Day	12% 10% 3 7% 6% 5% 4 3 5% 7% 38%	2200
October	1st to 10th	Day	8% 11% 3 7% 4 5% 6% 5% 7% 8% 36%	3356
	11th to 20th	Day	9% 10% 3 9% 5% 4 6% 5% 7% 9% 32%	2950
	21st to end	Day	5% 12% 4 9% 6% 4 5% 4 7% 8% 37%	3200
November	1st to 10th	Day	7% 15% 4 10% 7% 6% 6% 4 6% 6% 29%	1668
	11th to 20th	Day	4 10% 4 11% 6% 5% 5% 4 9% 9% 33%	1470
	21st to end	Day	3 13% 4 12% 8% 5% 5% 5% 9% 7% 29%	1470
December	1st to 10th	Day	5% 17% 5% 12% 8% 6% 6% 4 6% 8% 22%	2336
	11th to 20th	Day	6% 13% 5% 9% 7% 5% 6% 4 6% 9% 31%	2322
	21st to end	Day	1 9% 5% 13% 6% 5% 5% 3 5% 5% 42%	3058
January	1st to 10th	Night	4 13% 6% 15% 8% 6% 5% 4 6% 7% 26%	9366
	11th to 20th	Night	3 12% 4 11% 6% 5% 5% 4 7% 7% 36%	9003
	21st to end	Night	3 11% 5% 12% 7% 6% 5% 5% 7% 7% 32%	8994
February	1st to 10th	Night	4 12% 5% 14% 8% 7% 5% 5% 5% 6% 28%	2940
	11th to 20th	Night	3 13% 5% 12% 8% 6% 7% 5% 7% 7% 27%	2803
	21st to end	Night	2 12% 6% 12% 8% 7% 7% 5% 6% 6% 30%	2084
March	1st to 10th	Night	3 9% 5% 11% 8% 8% 5% 4 6% 8% 33%	5496
	11th to 20th	Night	3 11% 5% 11% 6% 5% 6% 5% 6% 10% 32%	5454
	21st to end	Night	9% 16% 7% 13% 5% 4 4 3 6% 7% 26%	5123
April	1st to 10th	Night	6% 15% 5% 11% 7% 6% 5% 4 8% 8% 26%	2010
	11th to 20th	Night	7% 17% 5% 11% 5% 6% 5% 3 6% 7% 27%	1821
	21st to end	Night	11% 14% 5% 10% 5% 5% 5% 3 6% 5% 30%	1650
May	1st to 10th	Night	13% 14% 4 7% 5% 4 4 4 6% 8% 31%	3640
	11th to 20th	Night	11% 12% 4 11% 6% 6% 6% 5% 6% 8% 25%	3209
	21st to end	Night	14% 10% 3 6% 4 4 4 3 6% 8% 38%	3388
June	1st to 10th	Night	18% 10% 4 7% 5% 4 4 5% 6% 7% 32%	1200
	11th to 20th	Night	20% 9% 4 8% 6% 6% 6% 5% 7% 7% 22%	1200
	21st to end	Night	15% 7% 2 8% 4 5% 6% 4 8% 8% 32%	1200
July	1st to 10th	Night	14% 6% 2 6% 4 4 5% 4 7% 7% 41%	2720
	11th to 20th	Night	16% 6% 2 5% 5% 5% 5% 5% 7% 7% 36%	2720
	21st to end	Night	14% 7% 2 6% 4 4 5% 4 6% 8% 41%	3773
August	1st to 10th	Night	15% 7% 2 5% 3 4 4 4 6% 6% 44%	2609
	11th to 20th	Night	17% 8% 3 7% 5% 5% 5% 4 5% 8% 33%	2577
	21st to end	Night	14% 8% 3 6% 3 5% 4 4 7% 8% 39%	3259
September	1st to 10th	Night	14% 8% 3 8% 3 4 4 4 5% 7% 40%	2000
	11th to 20th	Night	15% 9% 3 7% 4 3 4 3 6% 6% 40%	2079
	21st to end	Night	12% 8% 3 7% 4 4 5% 4 6% 7% 40%	2200
October	1st to 10th	Night	10% 12% 4 9% 6% 5% 5% 4 6% 9% 30%	3841
	11th to 20th	Night	8% 10% 4 8% 4 4 5% 4 6% 9% 38%	4197
	21st to end	Night	6% 11% 5% 10% 6% 5% 5% 4 6% 8% 35%	4600
November	1st to 10th	Night	8% 15% 4 9% 5% 4 5% 3 7% 8% 32%	2827
	11th to 20th	Night	4 12% 4 11% 7% 5% 5% 5% 6% 7% 33%	3150
	21st to end	Night	5% 13% 5% 11% 8% 6% 6% 4 7% 7% 29%	3150
December	1st to 10th	Night	5% 12% 4 13% 9% 7% 6% 4 5% 6% 28%	5061
	11th to 20th	Night	7% 15% 5% 10% 8% 7% 6% 5% 6% 6% 24%	6090
	21st to end	Night	2 12% 6% 11% 6% 5% 5% 4 7% 7% 34%	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	51% 8% 14% 15% 11% 1	3527
	11th to 20th	Day	41% 6% 14% 21% 15% 3	3942
	21st to end	Day	45% 10% 18% 18% 8%	5187
February	1st to 10th	Day	54% 8% 9% 14% 11% 2	1680
	11th to 20th	Day	54% 9% 11% 15% 9% 1	1707
	21st to end	Day	54% 8% 12% 14% 9% 2	1721
March	1st to 10th	Day	46% 8% 16% 15% 14%	4618
	11th to 20th	Day	38% 8% 15% 22% 16% 1	4764
	21st to end	Day	58% 9% 12% 12% 8% 1	6090
April	1st to 10th	Day	57% 12% 15% 12% 4	2413
	11th to 20th	Day	55% 9% 12% 16% 7%	2530
	21st to end	Day	55% 11% 13% 16% 4	2748
May	1st to 10th	Day	50% 8% 10% 19% 12% 1	6320
	11th to 20th	Day	54% 13% 14% 14% 5%	6687
	21st to end	Day	51% 11% 17% 16% 5% 1	7486
June	1st to 10th	Day	55% 10% 12% 15% 6% 2	3200
	11th to 20th	Day	62% 10% 11% 12% 4	3200
	21st to end	Day	52% 11% 14% 14% 6% 2	3200
July	1st to 10th	Day	42% 7% 15% 18% 13% 4	7161
	11th to 20th	Day	44% 7% 12% 25% 11% 1	7153
	21st to end	Day	44% 8% 20% 19% 9%	6865
August	1st to 10th	Day	39% 9% 15% 29% 8%	4524
	11th to 20th	Day	45% 8% 16% 22% 8%	4512
	21st to end	Day	44% 7% 20% 21% 7%	4647
September	1st to 10th	Day	42% 9% 18% 22% 7% 2	2400
	11th to 20th	Day	43% 8% 16% 23% 9% 2	2321
	21st to end	Day	44% 9% 18% 16% 11% 3	2200
October	1st to 10th	Day	43% 7% 22% 21% 7%	3356
	11th to 20th	Day	45% 9% 16% 23% 7%	2950
	21st to end	Day	44% 7% 19% 25% 5%	3200
November	1st to 10th	Day	52% 9% 13% 17% 8% 1	1668
	11th to 20th	Day	43% 11% 17% 18% 10% 1	1470
	21st to end	Day	49% 11% 18% 13% 6% 3	1470
December	1st to 10th	Day	60% 7% 15% 12% 5% 1	2336
	11th to 20th	Day	49% 7% 18% 17% 7% 1	2324
	21st to end	Day	40% 8% 12% 24% 14% 3	3058
January	1st to 10th	Night	55% 7% 11% 15% 11% 1	9367
	11th to 20th	Night	44% 6% 13% 19% 16% 2	9046
	21st to end	Night	45% 10% 21% 16% 8%	8994
February	1st to 10th	Night	54% 8% 11% 14% 11% 2	2940
	11th to 20th	Night	52% 9% 13% 15% 9% 1	2805
	21st to end	Night	50% 8% 12% 18% 10% 1	2084
March	1st to 10th	Night	47% 8% 15% 18% 12%	5496
	11th to 20th	Night	44% 7% 15% 21% 12%	5455
	21st to end	Night	54% 7% 11% 18% 10%	5123
April	1st to 10th	Night	51% 10% 17% 17% 6%	2010
	11th to 20th	Night	54% 9% 13% 16% 7% 1	1821
	21st to end	Night	51% 12% 13% 18% 6% 1	1650
May	1st to 10th	Night	47% 9% 13% 23% 7% 2	3637
	11th to 20th	Night	49% 12% 16% 17% 6%	3209
	21st to end	Night	40% 10% 20% 22% 6% 2	3388
June	1st to 10th	Night	49% 11% 15% 16% 8% 2	1200
	11th to 20th	Night	56% 12% 16% 13% 4	1200
	21st to end	Night	46% 12% 17% 18% 6% 1	1200
July	1st to 10th	Night	41% 6% 19% 18% 14% 3	2690
	11th to 20th	Night	45% 7% 16% 24% 7% 1	2684
	21st to end	Night	41% 6% 25% 20% 7%	3667
August	1st to 10th	Night	40% 7% 18% 32% 2	2601
	11th to 20th	Night	48% 7% 17% 22% 5%	2601
	21st to end	Night	42% 7% 21% 24% 5%	3259
September	1st to 10th	Night	41% 9% 17% 23% 7% 3	2000
	11th to 20th	Night	43% 7% 17% 24% 8% 2	2079
	21st to end	Night	40% 11% 18% 20% 10% 1	2200
October	1st to 10th	Night	50% 7% 20% 17% 6%	3841
	11th to 20th	Night	43% 6% 16% 26% 9%	4197
	21st to end	Night	45% 8% 19% 21% 7% 1	4600
November	1st to 10th	Night	47% 9% 15% 20% 9% 1	2827
	11th to 20th	Night	47% 9% 16% 17% 10% 1	3150
	21st to end	Night	51% 10% 14% 15% 8% 2	3150
December	1st to 10th	Night	56% 7% 15% 15% 6% 1	5061
	11th to 20th	Night	58% 8% 13% 15% 6%	6087
	21st to end	Night	44% 10% 14% 22% 9% 2	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	11% 13% 34% 29% 9% 4	220
	11th to 20th	Day	14% 16% 37% 24% 8% 2	220
	21st to end	Day	12% 23% 41% 19% 6%	242
February	1st to 10th	Day	16% 20% 33% 20% 8% 3	220
	11th to 20th	Day	9% 21% 35% 25% 8% 2	279
	21st to end	Day	11% 22% 33% 25% 8% 1	442
March	1st to 10th	Day	16% 23% 32% 18% 9% 2	540
	11th to 20th	Day	16% 19% 34% 20% 7% 3	540
	21st to end	Day	19% 21% 31% 19% 9% 2	594
April	1st to 10th	Day	18% 23% 32% 21% 5% 1	505
	11th to 20th	Day	18% 20% 27% 23% 8% 3	492
	21st to end	Day	17% 20% 33% 20% 9% 2	500
May	1st to 10th	Day	20% 18% 31% 22% 7% 2	503
	11th to 20th	Day	18% 12% 27% 26% 16% 2	700
	21st to end	Day	23% 10% 24% 25% 15% 4	817
June	1st to 10th	Day	22% 20% 29% 20% 8% 1	930
	11th to 20th	Day	25% 14% 25% 22% 13% 2	930
	21st to end	Day	19% 11% 25% 25% 16% 4	930
July	1st to 10th	Day	20% 10% 27% 26% 15% 2	916
	11th to 20th	Day	18% 12% 27% 25% 15% 2	912
	21st to end	Day	16% 11% 25% 26% 17% 5%	660
August	1st to 10th	Day	19% 9% 24% 30% 13% 5%	527
	11th to 20th	Day	16% 16% 30% 24% 10% 3	517
	21st to end	Day	19% 15% 30% 20% 14% 3	583
September	1st to 10th	Day	19% 16% 28% 25% 9% 4	530
	11th to 20th	Day	19% 16% 27% 24% 11% 3	530
	21st to end	Day	25% 26% 22% 19% 6% 1	530
October	1st to 10th	Day	25% 17% 28% 20% 8% 3	530
	11th to 20th	Day	20% 18% 31% 21% 8% 1	348
	21st to end	Day	21% 16% 35% 18% 8% 2	363
November	1st to 10th	Day	22% 21% 33% 17% 5% 2	259
	11th to 20th	Day	17% 17% 37% 22% 5% 1	220
	21st to end	Day	13% 19% 34% 22% 8% 4	220
December	1st to 10th	Day	14% 20% 31% 20% 10% 5%	220
	11th to 20th	Day	13% 17% 35% 25% 10%	220
	21st to end	Day	11% 14% 34% 29% 7% 3	242
January	1st to 10th	Night	15% 15% 37% 25% 8% 1	1160
	11th to 20th	Night	15% 18% 37% 22% 7% 1	1063
	21st to end	Night	13% 20% 36% 23% 7%	924
February	1st to 10th	Night	13% 16% 30% 26% 13% 1	840
	11th to 20th	Night	9% 16% 36% 29% 10%	824
	21st to end	Night	9% 16% 32% 28% 12% 2	692
March	1st to 10th	Night	11% 15% 31% 30% 11% 2	840
	11th to 20th	Night	9% 14% 37% 29% 10% 1	840
	21st to end	Night	13% 11% 33% 30% 12% 1	924
April	1st to 10th	Night	13% 12% 31% 31% 13%	804
	11th to 20th	Night	16% 11% 30% 31% 10% 1	633
	21st to end	Night	16% 12% 32% 28% 12%	450
May	1st to 10th	Night	19% 10% 21% 39% 12%	400
	11th to 20th	Night	13% 10% 22% 38% 16% 1	394
	21st to end	Night	21% 8% 21% 29% 19% 1	433
June	1st to 10th	Night	24% 8% 25% 30% 13% 1	400
	11th to 20th	Night	24% 7% 20% 31% 17% 1	400
	21st to end	Night	18% 8% 23% 28% 21% 3	400
July	1st to 10th	Night	18% 5% 18% 39% 19% 1	390
	11th to 20th	Night	19% 7% 21% 29% 24% 1	388
	21st to end	Night	13% 6% 17% 30% 32% 2	438
August	1st to 10th	Night	17% 3 16% 31% 30% 3	398
	11th to 20th	Night	16% 6% 18% 35% 24% 2	396
	21st to end	Night	17% 7% 23% 36% 16% 1	661
September	1st to 10th	Night	19% 7% 21% 35% 17% 1	800
	11th to 20th	Night	19% 6% 23% 34% 17% 1	800
	21st to end	Night	17% 15% 28% 29% 10% 1	800
October	1st to 10th	Night	19% 10% 29% 30% 11% 1	800
	11th to 20th	Night	17% 13% 32% 28% 10% 1	800
	21st to end	Night	15% 14% 38% 25% 7% 1	880
November	1st to 10th	Night	19% 16% 35% 23% 7%	852
	11th to 20th	Night	13% 19% 38% 24% 5%	1050
	21st to end	Night	13% 18% 38% 23% 6% 1	1050
December	1st to 10th	Night	13% 16% 41% 21% 9%	1056
	11th to 20th	Night	12% 15% 37% 27% 8% 1	1160
	21st to end	Night	11% 15% 40% 25% 8% 1	1276

Page generated at 2026-03-30 00:18:44. Version ac07

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