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 2024-01-31.

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	17% 8% 3 6% 6% 3 5% 5% 5% 7% 35%	74874
	Night	18% 10% 4 6% 5% 3 4 4 5% 6% 33%	75249
Transparency	Day	33% 39% 8% 13% 6% 1	74579
	Night	35% 38% 8% 12% 6% 1	75078
Seeing	Day	20% 14% 30% 22% 10% 3	13455
	Night	23% 13% 29% 24% 10% 1	22787

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	19% 15% 4 8% 7% 3 6% 4 5% 6% 23%	1517
	11th to 20th	Day	21% 15% 5% 9% 7% 4 3 4 4 4 24%	1520
	21st to end	Day	14% 15% 4 11% 7% 5% 7% 5% 5% 6% 22%	1815
February	1st to 10th	Day	19% 13% 6% 9% 8% 4 5% 4 5% 7% 21%	1620
	11th to 20th	Day	16% 13% 5% 10% 8% 3 5% 4 5% 5% 27%	1573
	21st to end	Day	22% 14% 4 7% 6% 3 4 4 6% 6% 25%	1473
March	1st to 10th	Day	16% 11% 5% 9% 8% 4 4 5% 4 4 30%	1840
	11th to 20th	Day	17% 12% 4 7% 7% 4 5% 4 4 5% 31%	1980
	21st to end	Day	21% 8% 3 6% 6% 3 3 4 5% 5% 37%	2264
April	1st to 10th	Day	20% 10% 3 6% 6% 3 4 4 4 7% 34%	2160
	11th to 20th	Day	19% 6% 3 5% 5% 3 4 4 4 7% 40%	2134
	21st to end	Day	21% 8% 3 6% 5% 3 4 5% 5% 6% 34%	2242
May	1st to 10th	Day	17% 8% 3 7% 6% 3 5% 6% 5% 7% 35%	2506
	11th to 20th	Day	15% 5% 3 5% 5% 3 4 5% 5% 8% 42%	2478
	21st to end	Day	13% 5% 2 5% 5% 3 5% 5% 6% 9% 41%	2725
June	1st to 10th	Day	18% 6% 3 5% 5% 4 4 4 7% 7% 36%	2520
	11th to 20th	Day	13% 5% 2 5% 5% 3 5% 5% 5% 9% 42%	2520
	21st to end	Day	14% 7% 3 5% 4 3 5% 4 5% 9% 41%	2520
July	1st to 10th	Day	10% 5% 2 4 4 3 4 5% 6% 9% 48%	2520
	11th to 20th	Day	11% 5% 2 5% 5% 3 4 5% 7% 9% 44%	2520
	21st to end	Day	11% 4 2 5% 6% 3 5% 6% 7% 10% 42%	2744
August	1st to 10th	Day	11% 4 2 4 5% 3 5% 5% 6% 9% 45%	2383
	11th to 20th	Day	11% 5% 2 4 6% 3 5% 6% 7% 10% 41%	2285
	21st to end	Day	13% 5% 2 5% 5% 3 4 5% 5% 10% 44%	2376
September	1st to 10th	Day	13% 5% 2 5% 4 3 5% 5% 6% 8% 44%	2160
	11th to 20th	Day	12% 6% 2 5% 4 3 4 3 5% 8% 48%	2160
	21st to end	Day	18% 6% 2 5% 5% 4 4 4 5% 8% 39%	1910
October	1st to 10th	Day	21% 8% 3 5% 5% 3 4 4 4 7% 37%	1800
	11th to 20th	Day	23% 6% 3 7% 5% 3 4 4 5% 7% 32%	1800
	21st to end	Day	28% 8% 4 6% 5% 3 4 5% 4 6% 26%	1890
November	1st to 10th	Day	18% 7% 3 5% 6% 3 5% 6% 6% 8% 33%	1671
	11th to 20th	Day	18% 9% 3 8% 7% 4 5% 5% 4 6% 31%	1530
	21st to end	Day	24% 12% 4 7% 6% 3 5% 4 6% 6% 23%	1520
December	1st to 10th	Day	24% 15% 4 7% 7% 3 5% 5% 4 7% 20%	1520
	11th to 20th	Day	21% 14% 5% 8% 6% 3 5% 4 4 6% 23%	1906
	21st to end	Day	28% 15% 5% 7% 6% 3 4 3 3 4 21%	2772
January	1st to 10th	Night	21% 15% 5% 9% 6% 4 4 4 4 5% 22%	2649
	11th to 20th	Night	20% 14% 5% 10% 7% 4 6% 5% 4 5% 20%	2660
	21st to end	Night	15% 14% 5% 10% 7% 3 5% 5% 4 5% 27%	2764
February	1st to 10th	Night	19% 15% 5% 10% 8% 3 5% 4 4 6% 22%	2340
	11th to 20th	Night	17% 12% 6% 8% 6% 3 4 4 4 6% 29%	2273
	21st to end	Night	20% 10% 4 8% 5% 3 5% 4 4 7% 29%	1781
March	1st to 10th	Night	16% 12% 6% 7% 6% 4 5% 4 4 5% 32%	2105
	11th to 20th	Night	20% 12% 4 6% 5% 3 4 3 4 6% 34%	1979
	21st to end	Night	19% 9% 4 7% 4 2 4 4 4 5% 38%	2091
April	1st to 10th	Night	21% 8% 3 6% 5% 3 4 4 5% 6% 35%	1800
	11th to 20th	Night	20% 7% 3 6% 4 3 4 4 5% 6% 38%	1775
	21st to end	Night	22% 9% 3 5% 5% 3 5% 4 4 7% 33%	1733
May	1st to 10th	Night	22% 7% 3 5% 4 4 4 5% 6% 5% 37%	1454
	11th to 20th	Night	13% 6% 2 5% 6% 3 4 4 5% 9% 42%	1415
	21st to end	Night	11% 5% 3 5% 5% 4 5% 5% 7% 9% 44%	1550
June	1st to 10th	Night	16% 6% 3 5% 5% 4 5% 5% 6% 8% 36%	1440
	11th to 20th	Night	13% 4 2 5% 5% 3 4 5% 6% 9% 43%	1440
	21st to end	Night	15% 6% 3 6% 5% 4 3 6% 4 7% 40%	1440
July	1st to 10th	Night	9% 5% 2 4 6% 4 5% 6% 5% 8% 47%	1440
	11th to 20th	Night	12% 4 3 5% 4 3 4 5% 7% 9% 44%	1440
	21st to end	Night	10% 5% 2 5% 5% 2 4 5% 7% 9% 46%	1574
August	1st to 10th	Night	9% 5% 2 5% 5% 3 4 5% 6% 8% 46%	1552
	11th to 20th	Night	12% 6% 2 5% 5% 3 5% 4 5% 9% 43%	1598
	21st to end	Night	12% 4 2 5% 5% 3 5% 5% 6% 8% 45%	1980
September	1st to 10th	Night	12% 6% 2 5% 4 3 4 4 5% 6% 48%	1800
	11th to 20th	Night	13% 4 3 4 4 2 4 3 6% 9% 50%	1800
	21st to end	Night	17% 5% 3 5% 4 2 4 4 5% 7% 43%	2046
October	1st to 10th	Night	18% 8% 3 6% 6% 4 4 5% 5% 7% 35%	2160
	11th to 20th	Night	21% 8% 3 6% 6% 4 4 4 4 6% 33%	2160
	21st to end	Night	24% 9% 4 8% 5% 4 4 5% 4 5% 28%	2466
November	1st to 10th	Night	20% 8% 3 5% 4 2 4 4 5% 6% 38%	2407
	11th to 20th	Night	19% 9% 4 5% 5% 3 4 5% 5% 8% 33%	2645
	21st to end	Night	22% 11% 3 7% 6% 3 5% 5% 5% 6% 25%	2660
December	1st to 10th	Night	22% 15% 5% 8% 6% 4 4 5% 5% 7% 21%	2660
	11th to 20th	Night	22% 13% 5% 7% 5% 3 3 4 4 5% 29%	3288
	21st to end	Night	32% 15% 4 6% 5% 3 4 4 5% 5% 18%	4884

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	40% 42% 6% 11% 2	1518
	11th to 20th	Day	43% 41% 6% 6% 5% 1	1520
	21st to end	Day	41% 38% 6% 9% 5% 1	1815
February	1st to 10th	Day	41% 38% 7% 11% 3 1	1620
	11th to 20th	Day	40% 39% 7% 8% 5% 1	1582
	21st to end	Day	42% 37% 7% 9% 5%	1473
March	1st to 10th	Day	37% 37% 9% 11% 5%	1843
	11th to 20th	Day	38% 37% 9% 10% 6% 1	1980
	21st to end	Day	31% 38% 6% 13% 9% 3	2264
April	1st to 10th	Day	33% 36% 7% 14% 8% 2	2160
	11th to 20th	Day	30% 37% 6% 15% 10% 1	2134
	21st to end	Day	35% 38% 6% 10% 8% 3	2242
May	1st to 10th	Day	31% 37% 7% 11% 11% 2	2506
	11th to 20th	Day	28% 38% 7% 14% 10% 2	2482
	21st to end	Day	25% 40% 10% 14% 8% 3	2725
June	1st to 10th	Day	31% 41% 9% 12% 7% 1	2520
	11th to 20th	Day	26% 39% 8% 19% 8% 1	2520
	21st to end	Day	29% 41% 12% 12% 6%	2520
July	1st to 10th	Day	23% 40% 10% 19% 7%	2450
	11th to 20th	Day	24% 40% 12% 17% 6%	2445
	21st to end	Day	25% 41% 12% 15% 7%	2591
August	1st to 10th	Day	26% 39% 11% 17% 7%	2369
	11th to 20th	Day	22% 40% 12% 17% 9% 1	2285
	21st to end	Day	25% 39% 8% 19% 8% 1	2376
September	1st to 10th	Day	26% 39% 10% 18% 7%	2160
	11th to 20th	Day	27% 37% 8% 20% 8%	2160
	21st to end	Day	31% 39% 7% 18% 5%	1910
October	1st to 10th	Day	32% 38% 8% 14% 8%	1800
	11th to 20th	Day	36% 40% 10% 10% 4	1800
	21st to end	Day	40% 39% 8% 9% 5%	1890
November	1st to 10th	Day	25% 43% 11% 14% 6%	1671
	11th to 20th	Day	35% 41% 7% 9% 6% 1	1530
	21st to end	Day	38% 43% 7% 7% 4	1520
December	1st to 10th	Day	42% 42% 7% 8% 1	1520
	11th to 20th	Day	44% 34% 12% 9% 1	1906
	21st to end	Day	54% 27% 5% 13% 1	2772
January	1st to 10th	Night	43% 41% 7% 7% 2	2649
	11th to 20th	Night	43% 42% 5% 6% 4	2660
	21st to end	Night	42% 37% 5% 10% 5% 1	2764
February	1st to 10th	Night	42% 39% 7% 8% 3	2340
	11th to 20th	Night	38% 38% 7% 12% 4	2275
	21st to end	Night	38% 38% 7% 11% 5% 1	1781
March	1st to 10th	Night	36% 38% 8% 14% 5%	2115
	11th to 20th	Night	36% 37% 9% 12% 6%	1980
	21st to end	Night	32% 37% 6% 11% 12% 2	2091
April	1st to 10th	Night	32% 37% 7% 13% 9% 2	1800
	11th to 20th	Night	34% 37% 7% 12% 10% 1	1775
	21st to end	Night	34% 37% 6% 11% 10% 3	1733
May	1st to 10th	Night	30% 37% 5% 11% 12% 4	1454
	11th to 20th	Night	25% 38% 7% 15% 12% 3	1416
	21st to end	Night	24% 39% 9% 14% 11% 2	1551
June	1st to 10th	Night	31% 39% 10% 13% 7%	1440
	11th to 20th	Night	23% 38% 11% 14% 11% 1	1440
	21st to end	Night	29% 41% 9% 15% 6%	1440
July	1st to 10th	Night	24% 41% 7% 16% 12% 1	1400
	11th to 20th	Night	25% 39% 9% 18% 8%	1392
	21st to end	Night	23% 41% 8% 19% 9% 1	1486
August	1st to 10th	Night	26% 39% 9% 18% 8%	1542
	11th to 20th	Night	23% 37% 9% 18% 11% 1	1598
	21st to end	Night	26% 39% 9% 17% 9%	1980
September	1st to 10th	Night	26% 37% 9% 18% 8% 1	1800
	11th to 20th	Night	22% 39% 10% 21% 8% 1	1800
	21st to end	Night	29% 38% 8% 18% 7% 1	2046
October	1st to 10th	Night	34% 38% 8% 12% 8%	2160
	11th to 20th	Night	37% 38% 9% 12% 4	2160
	21st to end	Night	38% 40% 9% 7% 6% 1	2466
November	1st to 10th	Night	27% 43% 9% 14% 7% 1	2407
	11th to 20th	Night	29% 43% 8% 12% 6% 2	2645
	21st to end	Night	38% 43% 7% 9% 3	2660
December	1st to 10th	Night	42% 42% 7% 7% 2	2660
	11th to 20th	Night	42% 35% 7% 11% 4	3288
	21st to end	Night	55% 27% 7% 9% 1	4884

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	28% 18% 31% 17% 6%	180
	11th to 20th	Day	32% 21% 28% 13% 4 1	180
	21st to end	Day	19% 24% 31% 21% 4	267
February	1st to 10th	Day	31% 25% 33% 10% 1	240
	11th to 20th	Day	24% 24% 40% 12%	240
	21st to end	Day	34% 20% 30% 15% 1	339
March	1st to 10th	Day	22% 17% 35% 20% 6%	420
	11th to 20th	Day	25% 19% 32% 20% 4	420
	21st to end	Day	30% 14% 32% 16% 6% 1	462
April	1st to 10th	Day	26% 20% 31% 18% 6%	420
	11th to 20th	Day	25% 19% 27% 17% 9% 4	412
	21st to end	Day	26% 13% 35% 17% 7% 2	420
May	1st to 10th	Day	23% 12% 33% 19% 11% 2	423
	11th to 20th	Day	17% 11% 33% 26% 11% 2	447
	21st to end	Day	17% 8% 33% 27% 11% 4	485
June	1st to 10th	Day	18% 12% 36% 23% 9% 3	450
	11th to 20th	Day	15% 11% 30% 29% 13% 3	450
	21st to end	Day	15% 9% 36% 25% 12% 3	450
July	1st to 10th	Day	11% 8% 26% 30% 21% 4	445
	11th to 20th	Day	13% 7% 26% 34% 15% 5%	444
	21st to end	Day	11% 7% 32% 35% 11% 2	488
August	1st to 10th	Day	12% 7% 27% 30% 20% 4	446
	11th to 20th	Day	11% 6% 25% 32% 19% 6%	439
	21st to end	Day	13% 11% 29% 25% 15% 7%	495
September	1st to 10th	Day	14% 9% 27% 30% 14% 6%	450
	11th to 20th	Day	12% 7% 28% 25% 18% 10%	450
	21st to end	Day	15% 13% 26% 24% 18% 4	450
October	1st to 10th	Day	24% 15% 25% 18% 13% 5%	450
	11th to 20th	Day	24% 19% 29% 19% 7% 2	450
	21st to end	Day	30% 20% 27% 18% 5%	450
November	1st to 10th	Day	26% 20% 28% 19% 7% 1	365
	11th to 20th	Day	25% 19% 36% 11% 7% 2	190
	21st to end	Day	24% 25% 35% 9% 6% 1	180
December	1st to 10th	Day	29% 22% 31% 12% 6% 1	180
	11th to 20th	Day	25% 29% 33% 11% 2	180
	21st to end	Day	33% 22% 29% 13% 4	198
January	1st to 10th	Night	30% 20% 28% 17% 4	760
	11th to 20th	Night	30% 18% 29% 18% 5% 1	760
	21st to end	Night	24% 16% 31% 24% 5%	835
February	1st to 10th	Night	24% 21% 35% 17% 3	720
	11th to 20th	Night	22% 17% 37% 19% 5%	703
	21st to end	Night	27% 19% 30% 20% 4	592
March	1st to 10th	Night	23% 15% 34% 23% 4	720
	11th to 20th	Night	26% 16% 29% 23% 5% 1	720
	21st to end	Night	23% 12% 34% 22% 8% 1	792
April	1st to 10th	Night	25% 13% 32% 25% 4	720
	11th to 20th	Night	22% 15% 34% 21% 8% 1	711
	21st to end	Night	25% 11% 27% 26% 10% 1	653
May	1st to 10th	Night	26% 5% 25% 31% 11% 1	374
	11th to 20th	Night	14% 7% 34% 33% 10% 1	354
	21st to end	Night	10% 8% 31% 32% 18% 1	389
June	1st to 10th	Night	18% 7% 26% 35% 14% 1	360
	11th to 20th	Night	13% 8% 27% 37% 15% 1	360
	21st to end	Night	16% 7% 25% 33% 18% 1	360
July	1st to 10th	Night	9% 3 26% 37% 23% 1	350
	11th to 20th	Night	12% 5% 23% 37% 22% 2	348
	21st to end	Night	11% 4 26% 44% 14% 2	394
August	1st to 10th	Night	11% 3 25% 35% 24% 2	478
	11th to 20th	Night	14% 4 21% 31% 26% 4	534
	21st to end	Night	12% 6% 28% 33% 20% 2	792
September	1st to 10th	Night	14% 8% 27% 30% 18% 3	720
	11th to 20th	Night	13% 8% 20% 31% 22% 6%	720
	21st to end	Night	18% 10% 24% 26% 18% 4	720
October	1st to 10th	Night	22% 15% 26% 18% 17% 3	720
	11th to 20th	Night	26% 16% 27% 23% 8% 1	720
	21st to end	Night	29% 14% 30% 22% 5%	792
November	1st to 10th	Night	27% 14% 28% 21% 9% 1	740
	11th to 20th	Night	24% 22% 31% 15% 8% 1	760
	21st to end	Night	30% 19% 29% 15% 6%	760
December	1st to 10th	Night	32% 21% 25% 18% 3	760
	11th to 20th	Night	26% 22% 33% 15% 3 1	760
	21st to end	Night	35% 16% 31% 15% 2	836

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