Kingston
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kingston clear sky chart from 2005-11-06 to 2026-06-16.

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	16% 9% 3 8% 5% 4 4 4 5% 7% 34%	138162
	Night	18% 11% 4 8% 5% 5% 4 4 5% 6% 31%	133840
Transparency	Day	48% 7% 13% 21% 10% 1	141668
	Night	52% 6% 11% 19% 11% 1	138410
Seeing	Day	20% 14% 30% 23% 10% 3	16518
	Night	22% 13% 29% 24% 10% 1	25736

By Month

Percentage Cloud Cover NE (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	15% 15% 5% 10% 6% 5% 5% 4 5% 5% 24%	4661
	11th to 20th	Day	13% 18% 8% 17% 8% 5% 4 3 4 4 16%	4650
	21st to end	Day	11% 15% 6% 15% 7% 6% 6% 4 5% 6% 20%	5600
February	1st to 10th	Day	17% 14% 5% 10% 7% 4 4 3 5% 6% 23%	1890
	11th to 20th	Day	15% 14% 4 11% 7% 5% 4 3 5% 5% 26%	1843
	21st to end	Day	20% 15% 4 8% 6% 4 4 3 5% 6% 23%	1722
March	1st to 10th	Day	20% 11% 4 8% 5% 4 4 3 4 5% 33%	4705
	11th to 20th	Day	11% 11% 4 9% 6% 6% 5% 4 6% 7% 32%	5090
	21st to end	Day	20% 8% 3 7% 5% 4 4 3 5% 5% 37%	5816
April	1st to 10th	Day	20% 12% 3 8% 5% 4 4 3 4 6% 32%	2520
	11th to 20th	Day	21% 8% 3 6% 4 4 4 3 4 6% 37%	2494
	21st to end	Day	21% 9% 3 6% 4 4 4 3 5% 6% 34%	2617
May	1st to 10th	Day	22% 9% 3 8% 4 4 4 3 5% 7% 30%	8195
	11th to 20th	Day	15% 7% 3 8% 5% 4 5% 4 5% 7% 37%	8221
	21st to end	Day	20% 7% 2 7% 4 4 5% 4 6% 7% 33%	9060
June	1st to 10th	Day	17% 6% 3 6% 5% 5% 4 3 7% 7% 36%	2940
	11th to 20th	Day	13% 6% 2 5% 5% 5% 4 5% 6% 8% 40%	2870
	21st to end	Day	15% 7% 2 6% 4 4 5% 3 5% 8% 40%	2800
July	1st to 10th	Day	11% 6% 3 6% 4 4 4 4 6% 9% 43%	6360
	11th to 20th	Day	10% 5% 2 6% 4 4 5% 4 6% 9% 46%	6360
	21st to end	Day	10% 4 2 5% 4 4 4 5% 7% 9% 46%	6926
August	1st to 10th	Day	16% 7% 2 5% 4 4 4 3 5% 8% 42%	4335
	11th to 20th	Day	16% 5% 2 5% 4 4 4 4 7% 10% 39%	4141
	21st to end	Day	15% 4 2 5% 4 4 4 4 6% 9% 43%	4312
September	1st to 10th	Day	13% 5% 2 6% 3 4 5% 4 6% 8% 45%	2400
	11th to 20th	Day	11% 6% 2 6% 4 4 3 3 5% 8% 50%	2400
	21st to end	Day	18% 6% 2 7% 4 5% 4 4 5% 7% 38%	2120
October	1st to 10th	Day	19% 7% 2 6% 4 3 4 4 4 6% 39%	2000
	11th to 20th	Day	21% 7% 3 7% 5% 4 4 3 5% 7% 33%	2000
	21st to end	Day	26% 8% 4 7% 4 4 5% 4 5% 7% 27%	2099
November	1st to 10th	Day	17% 8% 2 7% 5% 4 5% 5% 5% 8% 34%	1851
	11th to 20th	Day	17% 11% 3 8% 6% 5% 4 4 4 6% 31%	1690
	21st to end	Day	23% 14% 3 9% 5% 4 4 3 6% 5% 23%	1680
December	1st to 10th	Day	21% 16% 3 10% 5% 5% 4 4 5% 6% 20%	2680
	11th to 20th	Day	20% 15% 5% 11% 5% 5% 4 3 4 5% 23%	3066
	21st to end	Day	23% 14% 4 9% 5% 4 4 3 4 5% 24%	4048
January	1st to 10th	Night	15% 16% 6% 12% 6% 6% 5% 3 5% 5% 22%	8234
	11th to 20th	Night	15% 16% 7% 17% 8% 6% 5% 3 4 5% 15%	8235
	21st to end	Night	14% 15% 7% 12% 6% 6% 5% 4 5% 5% 22%	8563
February	1st to 10th	Night	17% 15% 5% 10% 6% 5% 5% 3 4 6% 24%	2730
	11th to 20th	Night	16% 13% 5% 10% 5% 4 4 3 5% 6% 29%	2663
	21st to end	Night	18% 12% 4 9% 5% 4 5% 4 4 7% 28%	2082
March	1st to 10th	Night	20% 11% 4 8% 5% 5% 4 3 4 5% 31%	5353
	11th to 20th	Night	16% 12% 3 7% 4 4 4 3 5% 8% 33%	5089
	21st to end	Night	22% 10% 3 7% 3 3 4 3 4 6% 36%	5357
April	1st to 10th	Night	21% 9% 3 7% 5% 3 4 4 5% 6% 34%	2100
	11th to 20th	Night	20% 9% 3 7% 3 4 4 4 5% 5% 36%	2075
	21st to end	Night	21% 9% 3 6% 4 5% 4 3 4 6% 35%	2021
May	1st to 10th	Night	26% 9% 3 8% 4 5% 4 4 5% 6% 26%	4702
	11th to 20th	Night	17% 8% 3 8% 5% 5% 5% 3 5% 7% 34%	4639
	21st to end	Night	18% 7% 3 6% 4 4 5% 4 6% 7% 35%	5114
June	1st to 10th	Night	16% 7% 3 7% 4 5% 5% 4 6% 7% 36%	1680
	11th to 20th	Night	12% 5% 1 7% 6% 4 5% 4 7% 9% 42%	1640
	21st to end	Night	16% 7% 3 6% 5% 5% 4 4 5% 6% 39%	1600
July	1st to 10th	Night	11% 6% 3 6% 5% 5% 6% 5% 6% 9% 38%	3600
	11th to 20th	Night	12% 6% 2 6% 4 4 4 3 6% 8% 45%	3600
	21st to end	Night	10% 5% 2 5% 4 3 4 3 6% 9% 48%	3926
August	1st to 10th	Night	11% 6% 2 7% 4 4 4 3 7% 9% 44%	2811
	11th to 20th	Night	14% 6% 2 6% 4 4 4 3 6% 9% 44%	2875
	21st to end	Night	10% 4 2 5% 4 5% 5% 5% 8% 9% 42%	3586
September	1st to 10th	Night	11% 6% 2 6% 3 4 4 3 5% 6% 49%	2000
	11th to 20th	Night	12% 4 2 4 4 3 4 3 6% 8% 52%	2000
	21st to end	Night	18% 5% 3 5% 4 4 4 3 5% 7% 42%	2275
October	1st to 10th	Night	17% 8% 2 7% 5% 5% 4 4 5% 7% 38%	2400
	11th to 20th	Night	19% 9% 3 7% 6% 4 4 3 5% 6% 34%	2400
	21st to end	Night	23% 9% 3 9% 4 5% 4 4 4 5% 30%	2740
November	1st to 10th	Night	19% 9% 2 6% 4 4 4 3 5% 6% 38%	2667
	11th to 20th	Night	18% 10% 3 6% 4 4 4 4 5% 7% 34%	2925
	21st to end	Night	21% 12% 3 9% 6% 5% 5% 4 5% 6% 24%	2940
December	1st to 10th	Night	21% 17% 4 9% 6% 5% 5% 4 5% 6% 20%	4720
	11th to 20th	Night	22% 15% 4 8% 4 4 3 3 4 5% 29%	5348
	21st to end	Night	28% 15% 3 8% 4 4 4 4 5% 5% 20%	7150

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	60% 7% 11% 15% 6% 1	4662
	11th to 20th	Day	71% 6% 8% 8% 6% 1	4680
	21st to end	Day	65% 6% 10% 11% 8% 1	5600
February	1st to 10th	Day	60% 7% 10% 16% 5% 1	1890
	11th to 20th	Day	58% 6% 10% 16% 9% 1	1852
	21st to end	Day	60% 6% 12% 13% 8% 1	1722
March	1st to 10th	Day	53% 5% 11% 15% 14% 2	4708
	11th to 20th	Day	49% 5% 22% 12% 10% 1	5090
	21st to end	Day	48% 5% 8% 21% 16% 2	5816
April	1st to 10th	Day	53% 5% 9% 18% 13% 2	2520
	11th to 20th	Day	47% 6% 9% 22% 15% 2	2494
	21st to end	Day	50% 6% 11% 18% 12% 3	2617
May	1st to 10th	Day	52% 6% 11% 20% 9% 1	8207
	11th to 20th	Day	45% 7% 13% 22% 12% 1	8225
	21st to end	Day	47% 7% 12% 24% 9% 1	9061
June	1st to 10th	Day	44% 8% 13% 20% 13% 1	2940
	11th to 20th	Day	39% 9% 12% 27% 12% 2	2870
	21st to end	Day	40% 9% 15% 22% 13% 1	2800
July	1st to 10th	Day	37% 6% 14% 30% 13% 1	6290
	11th to 20th	Day	34% 7% 16% 30% 13% 1	6285
	21st to end	Day	32% 8% 15% 35% 9%	6728
August	1st to 10th	Day	40% 6% 16% 24% 12% 1	4321
	11th to 20th	Day	38% 8% 17% 27% 10% 1	4180
	21st to end	Day	35% 8% 16% 31% 10%	4312
September	1st to 10th	Day	36% 8% 15% 29% 11% 1	2400
	11th to 20th	Day	34% 5% 13% 30% 17% 1	2400
	21st to end	Day	45% 8% 12% 26% 9%	2120
October	1st to 10th	Day	42% 6% 12% 29% 11%	3260
	11th to 20th	Day	43% 7% 16% 26% 7% 1	3240
	21st to end	Day	47% 8% 15% 22% 8%	3363
November	1st to 10th	Day	48% 9% 14% 20% 9% 1	1851
	11th to 20th	Day	54% 7% 12% 17% 9% 1	1690
	21st to end	Day	62% 9% 12% 10% 7%	1680
December	1st to 10th	Day	65% 6% 16% 9% 3	2680
	11th to 20th	Day	63% 6% 12% 13% 6%	3066
	21st to end	Day	62% 6% 11% 16% 4	4048
January	1st to 10th	Night	63% 7% 11% 13% 6%	8234
	11th to 20th	Night	72% 7% 6% 9% 6%	8280
	21st to end	Night	64% 6% 8% 12% 10% 1	8563
February	1st to 10th	Night	62% 7% 11% 14% 6% 1	2730
	11th to 20th	Night	57% 5% 11% 18% 9%	2665
	21st to end	Night	55% 6% 12% 18% 8% 1	2082
March	1st to 10th	Night	54% 5% 8% 17% 12% 4	5363
	11th to 20th	Night	49% 6% 17% 17% 9% 3	5090
	21st to end	Night	50% 4 7% 20% 17% 2	5357
April	1st to 10th	Night	51% 4 10% 20% 13% 2	2100
	11th to 20th	Night	49% 6% 10% 18% 16% 1	2075
	21st to end	Night	49% 6% 9% 18% 15% 3	2021
May	1st to 10th	Night	58% 5% 8% 15% 10% 2	4708
	11th to 20th	Night	48% 7% 11% 20% 12% 1	4640
	21st to end	Night	45% 6% 12% 21% 15% 2	5115
June	1st to 10th	Night	45% 7% 11% 22% 13% 1	1680
	11th to 20th	Night	37% 8% 15% 20% 19% 3	1640
	21st to end	Night	43% 9% 12% 22% 14% 1	1600
July	1st to 10th	Night	40% 7% 15% 21% 17% 1	3560
	11th to 20th	Night	37% 6% 11% 32% 13% 1	3552
	21st to end	Night	33% 7% 12% 32% 15% 1	3809
August	1st to 10th	Night	37% 7% 14% 28% 13% 1	2801
	11th to 20th	Night	38% 6% 14% 30% 11% 1	2902
	21st to end	Night	33% 9% 14% 32% 11% 1	3586
September	1st to 10th	Night	36% 7% 13% 31% 13% 1	2000
	11th to 20th	Night	31% 7% 13% 33% 16% 1	2000
	21st to end	Night	42% 6% 11% 28% 13% 1	2275
October	1st to 10th	Night	40% 6% 11% 27% 16% 1	3920
	11th to 20th	Night	42% 5% 15% 28% 10%	3899
	21st to end	Night	50% 5% 14% 23% 8% 1	4413
November	1st to 10th	Night	47% 7% 13% 21% 11% 1	2667
	11th to 20th	Night	50% 7% 11% 19% 10% 2	2925
	21st to end	Night	60% 9% 12% 14% 5%	2940
December	1st to 10th	Night	65% 7% 12% 13% 3	4720
	11th to 20th	Night	59% 5% 11% 14% 10% 1	5348
	21st to end	Night	65% 6% 9% 12% 8%	7150

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	27% 15% 35% 16% 6%	220
	11th to 20th	Day	32% 22% 26% 15% 4 1	220
	21st to end	Day	19% 22% 32% 22% 5% 1	330
February	1st to 10th	Day	27% 23% 30% 16% 4	330
	11th to 20th	Day	22% 22% 40% 13% 3	330
	21st to end	Day	30% 20% 31% 18% 1	438
March	1st to 10th	Day	23% 16% 34% 20% 6%	540
	11th to 20th	Day	25% 19% 33% 19% 4	540
	21st to end	Day	29% 16% 33% 16% 6% 1	594
April	1st to 10th	Day	27% 18% 32% 17% 6%	540
	11th to 20th	Day	26% 20% 27% 16% 9% 3	532
	21st to end	Day	25% 14% 33% 19% 7% 2	540
May	1st to 10th	Day	22% 14% 32% 20% 11% 1	543
	11th to 20th	Day	16% 10% 33% 28% 11% 2	567
	21st to end	Day	19% 9% 32% 27% 11% 3	617
June	1st to 10th	Day	17% 11% 34% 24% 11% 2	570
	11th to 20th	Day	14% 10% 31% 29% 13% 3	550
	21st to end	Day	16% 9% 35% 26% 11% 2	530
July	1st to 10th	Day	11% 8% 27% 32% 19% 3	525
	11th to 20th	Day	12% 7% 26% 35% 15% 4	524
	21st to end	Day	11% 7% 31% 36% 12% 3	576
August	1st to 10th	Day	12% 7% 26% 30% 21% 4	526
	11th to 20th	Day	13% 7% 24% 31% 20% 7%	519
	21st to end	Day	13% 10% 29% 27% 15% 6%	583
September	1st to 10th	Day	13% 10% 25% 30% 15% 6%	530
	11th to 20th	Day	10% 6% 24% 25% 22% 13%	530
	21st to end	Day	17% 12% 25% 25% 17% 4	530
October	1st to 10th	Day	22% 14% 25% 21% 14% 5%	530
	11th to 20th	Day	22% 18% 32% 18% 8% 2	530
	21st to end	Day	28% 19% 28% 19% 6%	527
November	1st to 10th	Day	26% 20% 29% 18% 6% 1	425
	11th to 20th	Day	23% 18% 37% 12% 8% 2	230
	21st to end	Day	28% 24% 35% 8% 5%	220
December	1st to 10th	Day	30% 21% 31% 12% 6%	220
	11th to 20th	Day	25% 28% 33% 12% 2	220
	21st to end	Day	31% 22% 27% 14% 6%	242
January	1st to 10th	Night	28% 19% 31% 17% 4	840
	11th to 20th	Night	30% 18% 29% 18% 5%	840
	21st to end	Night	23% 16% 31% 24% 5%	924
February	1st to 10th	Night	22% 20% 34% 20% 3	840
	11th to 20th	Night	22% 17% 36% 20% 5%	823
	21st to end	Night	26% 19% 30% 21% 4	692
March	1st to 10th	Night	23% 15% 34% 23% 5%	840
	11th to 20th	Night	26% 17% 28% 23% 5% 1	840
	21st to end	Night	25% 11% 34% 22% 7% 1	924
April	1st to 10th	Night	25% 13% 32% 26% 4	840
	11th to 20th	Night	23% 15% 32% 22% 7% 1	831
	21st to end	Night	24% 11% 27% 26% 10% 1	761
May	1st to 10th	Night	27% 6% 24% 31% 11% 1	436
	11th to 20th	Night	15% 7% 32% 33% 12% 1	414
	21st to end	Night	11% 8% 31% 32% 17% 1	455
June	1st to 10th	Night	17% 7% 25% 36% 14% 1	420
	11th to 20th	Night	12% 7% 27% 38% 15% 1	410
	21st to end	Night	17% 7% 26% 33% 17% 1	400
July	1st to 10th	Night	10% 3 26% 38% 22% 2	390
	11th to 20th	Night	11% 5% 22% 36% 22% 3	388
	21st to end	Night	11% 4 24% 43% 16% 1	438
August	1st to 10th	Night	11% 3 24% 36% 24% 2	532
	11th to 20th	Night	14% 4 21% 30% 26% 4	594
	21st to end	Night	12% 5% 26% 34% 21% 2	880
September	1st to 10th	Night	13% 8% 26% 31% 19% 3	800
	11th to 20th	Night	12% 7% 19% 30% 24% 8%	800
	21st to end	Night	19% 9% 22% 28% 19% 4	800
October	1st to 10th	Night	21% 14% 26% 19% 18% 3	800
	11th to 20th	Night	25% 16% 27% 23% 8% 2	800
	21st to end	Night	28% 14% 30% 22% 5%	880
November	1st to 10th	Night	26% 15% 28% 21% 9% 1	820
	11th to 20th	Night	23% 22% 31% 16% 8% 1	840
	21st to end	Night	30% 20% 29% 15% 6%	840
December	1st to 10th	Night	31% 20% 26% 18% 4	840
	11th to 20th	Night	26% 22% 33% 15% 3 1	840
	21st to end	Night	35% 16% 30% 15% 3	924

Page generated at 2026-06-13 02:31:38. Version ac07

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