Gananoque
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Gananoque clear sky chart from 2005-11-06 to 2026-05-02.

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	16% 10% 4 9% 5% 4 4 4 5% 7% 32%	132055
	Night	17% 11% 4 9% 5% 5% 4 3 5% 6% 30%	130435
Transparency	Day	51% 7% 12% 20% 10% 1	135559
	Night	55% 6% 11% 18% 9% 1	135018
Seeing	Day	23% 15% 30% 20% 9% 2	16348
	Night	24% 13% 29% 24% 9% 1	25630

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	14% 17% 6% 14% 6% 4 4 4 4 5% 22%	4661
	11th to 20th	Day	12% 20% 9% 16% 7% 5% 4 3 4 4 17%	4650
	21st to end	Day	11% 16% 7% 16% 8% 8% 5% 3 4 4 18%	5539
February	1st to 10th	Day	15% 16% 5% 11% 7% 6% 5% 4 4 5% 21%	1890
	11th to 20th	Day	15% 14% 6% 11% 6% 5% 5% 3 5% 4 25%	1850
	21st to end	Day	19% 16% 5% 10% 7% 5% 5% 3 4 4 22%	1730
March	1st to 10th	Day	20% 13% 4 10% 5% 4 4 3 3 5% 29%	4657
	11th to 20th	Day	11% 13% 4 10% 5% 5% 5% 4 5% 6% 31%	5090
	21st to end	Day	20% 10% 3 8% 5% 4 3 3 4 5% 36%	5857
April	1st to 10th	Day	20% 13% 4 8% 5% 4 4 3 3 6% 31%	2520
	11th to 20th	Day	21% 9% 3 7% 4 4 4 3 4 6% 36%	2494
	21st to end	Day	21% 10% 4 7% 4 4 5% 3 4 5% 33%	2604
May	1st to 10th	Day	25% 11% 4 8% 5% 4 4 3 5% 6% 25%	6360
	11th to 20th	Day	16% 9% 3 8% 5% 5% 4 4 6% 7% 34%	6318
	21st to end	Day	20% 8% 3 7% 4 4 5% 4 6% 7% 33%	6949
June	1st to 10th	Day	18% 9% 3 7% 5% 5% 5% 3 5% 8% 33%	2800
	11th to 20th	Day	14% 6% 2 5% 5% 5% 5% 5% 6% 8% 38%	2800
	21st to end	Day	16% 7% 2 7% 5% 5% 5% 4 6% 8% 36%	2800
July	1st to 10th	Day	11% 7% 2 7% 5% 5% 5% 4 7% 10% 39%	6360
	11th to 20th	Day	11% 6% 2 6% 4 4 5% 4 7% 8% 43%	6360
	21st to end	Day	10% 5% 2 5% 4 4 5% 4 7% 9% 44%	6926
August	1st to 10th	Day	15% 7% 2 7% 4 4 4 4 6% 8% 39%	4376
	11th to 20th	Day	17% 6% 2 5% 4 4 5% 4 7% 9% 37%	4113
	21st to end	Day	15% 5% 2 6% 4 4 4 4 6% 9% 40%	4312
September	1st to 10th	Day	12% 6% 2 6% 4 4 4 4 6% 8% 44%	2400
	11th to 20th	Day	10% 6% 2 6% 4 4 4 3 5% 7% 49%	2400
	21st to end	Day	17% 7% 3 6% 4 5% 4 4 6% 6% 38%	2128
October	1st to 10th	Day	20% 7% 3 7% 4 3 4 3 5% 6% 38%	2000
	11th to 20th	Day	19% 10% 3 8% 5% 5% 5% 3 5% 7% 31%	2000
	21st to end	Day	25% 10% 3 7% 6% 5% 4 3 5% 5% 28%	2080
November	1st to 10th	Day	16% 9% 4 7% 6% 5% 4 4 6% 7% 32%	1851
	11th to 20th	Day	15% 13% 4 9% 5% 5% 5% 3 5% 6% 31%	1706
	21st to end	Day	22% 14% 4 9% 5% 5% 4 3 6% 6% 22%	1680
December	1st to 10th	Day	20% 17% 5% 13% 5% 5% 4 3 4 5% 18%	2680
	11th to 20th	Day	19% 18% 6% 12% 5% 4 3 3 4 4 22%	3066
	21st to end	Day	23% 15% 5% 11% 5% 4 4 3 3 5% 22%	4048
January	1st to 10th	Night	16% 17% 6% 13% 6% 5% 4 3 4 5% 21%	8234
	11th to 20th	Night	14% 18% 8% 15% 7% 6% 5% 3 4 4 15%	8235
	21st to end	Night	15% 14% 7% 12% 6% 7% 5% 3 5% 5% 21%	8640
February	1st to 10th	Night	16% 14% 5% 13% 7% 6% 4 4 4 5% 22%	2730
	11th to 20th	Night	15% 14% 5% 10% 7% 5% 4 3 4 6% 28%	2654
	21st to end	Night	18% 14% 4 11% 5% 5% 4 4 5% 5% 26%	2076
March	1st to 10th	Night	21% 12% 4 9% 5% 6% 3 3 4 5% 29%	5401
	11th to 20th	Night	16% 13% 3 7% 4 4 4 4 6% 8% 31%	5089
	21st to end	Night	22% 11% 3 9% 4 3 3 3 4 5% 32%	5316
April	1st to 10th	Night	21% 10% 3 7% 4 4 3 4 4 6% 33%	2100
	11th to 20th	Night	21% 9% 3 6% 4 4 4 3 4 6% 35%	2075
	21st to end	Night	22% 9% 3 7% 4 4 4 3 4 6% 33%	2034
May	1st to 10th	Night	27% 11% 3 8% 5% 4 4 3 5% 6% 25%	3602
	11th to 20th	Night	16% 9% 3 8% 5% 4 4 3 5% 7% 36%	3575
	21st to end	Night	19% 9% 3 7% 4 4 5% 4 5% 7% 34%	3926
June	1st to 10th	Night	16% 7% 3 7% 6% 5% 5% 3 6% 9% 33%	1600
	11th to 20th	Night	13% 5% 3 6% 5% 4 5% 4 6% 8% 41%	1600
	21st to end	Night	18% 6% 3 6% 4 4 5% 5% 5% 8% 36%	1600
July	1st to 10th	Night	12% 6% 2 7% 5% 5% 5% 5% 7% 9% 37%	3600
	11th to 20th	Night	13% 7% 2 6% 4 4 4 3 6% 8% 43%	3600
	21st to end	Night	9% 6% 2 6% 4 4 4 4 6% 8% 48%	3926
August	1st to 10th	Night	11% 7% 3 7% 4 4 5% 4 6% 8% 41%	2770
	11th to 20th	Night	14% 7% 3 5% 5% 3 4 3 5% 8% 42%	2903
	21st to end	Night	10% 4 2 7% 5% 5% 5% 5% 7% 9% 39%	3586
September	1st to 10th	Night	12% 6% 2 7% 4 4 4 4 5% 6% 47%	2000
	11th to 20th	Night	12% 6% 1 5% 3 3 3 3 6% 7% 50%	2000
	21st to end	Night	16% 6% 2 6% 4 4 4 3 6% 6% 41%	2269
October	1st to 10th	Night	18% 8% 3 7% 4 3 4 4 5% 7% 38%	2400
	11th to 20th	Night	19% 8% 3 7% 6% 5% 5% 3 5% 7% 33%	2400
	21st to end	Night	24% 9% 3 8% 5% 5% 4 3 5% 5% 30%	2760
November	1st to 10th	Night	18% 10% 3 7% 4 3 4 3 5% 6% 36%	2667
	11th to 20th	Night	17% 11% 3 7% 4 4 5% 4 5% 7% 32%	2909
	21st to end	Night	21% 14% 3 9% 5% 4 6% 4 5% 6% 23%	2940
December	1st to 10th	Night	19% 17% 4 12% 7% 6% 5% 4 5% 5% 17%	4720
	11th to 20th	Night	23% 15% 4 9% 5% 4 3 3 4 4 27%	5348
	21st to end	Night	28% 14% 4 11% 4 4 3 3 4 5% 19%	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	66% 7% 9% 13% 4	4662
	11th to 20th	Day	74% 6% 7% 6% 7% 1	4680
	21st to end	Day	69% 6% 9% 9% 6% 1	5539
February	1st to 10th	Day	64% 7% 10% 14% 4 1	1890
	11th to 20th	Day	61% 6% 10% 15% 6% 1	1859
	21st to end	Day	65% 7% 8% 12% 7% 1	1730
March	1st to 10th	Day	57% 4 11% 13% 12% 2	4660
	11th to 20th	Day	51% 7% 18% 13% 10% 1	5090
	21st to end	Day	50% 6% 8% 18% 15% 2	5857
April	1st to 10th	Day	55% 5% 9% 18% 12% 2	2520
	11th to 20th	Day	49% 5% 8% 21% 14% 2	2494
	21st to end	Day	52% 6% 10% 17% 13% 3	2604
May	1st to 10th	Day	58% 7% 9% 17% 8% 1	6371
	11th to 20th	Day	48% 9% 12% 18% 13% 1	6322
	21st to end	Day	49% 8% 13% 21% 9% 1	6949
June	1st to 10th	Day	48% 7% 13% 19% 12% 1	2800
	11th to 20th	Day	42% 8% 12% 26% 11% 2	2800
	21st to end	Day	44% 9% 14% 21% 12% 1	2800
July	1st to 10th	Day	39% 6% 13% 30% 12%	6290
	11th to 20th	Day	36% 7% 15% 28% 13% 1	6285
	21st to end	Day	34% 7% 14% 34% 10%	6728
August	1st to 10th	Day	43% 6% 15% 23% 12% 1	4362
	11th to 20th	Day	42% 8% 16% 25% 9% 1	4152
	21st to end	Day	39% 7% 15% 30% 9%	4312
September	1st to 10th	Day	37% 8% 15% 28% 12% 1	2400
	11th to 20th	Day	35% 6% 13% 30% 16% 1	2400
	21st to end	Day	45% 7% 13% 24% 10%	2128
October	1st to 10th	Day	44% 5% 12% 28% 10%	3260
	11th to 20th	Day	48% 5% 15% 24% 7%	3240
	21st to end	Day	49% 6% 14% 23% 7%	3344
November	1st to 10th	Day	51% 7% 15% 19% 7% 1	1851
	11th to 20th	Day	56% 7% 11% 16% 7% 2	1706
	21st to end	Day	64% 8% 13% 8% 6%	1680
December	1st to 10th	Day	71% 7% 13% 8% 2	2680
	11th to 20th	Day	68% 6% 9% 12% 5%	3066
	21st to end	Day	66% 6% 10% 14% 4	4048
January	1st to 10th	Night	69% 6% 10% 11% 4	8234
	11th to 20th	Night	75% 7% 6% 8% 4	8280
	21st to end	Night	67% 6% 9% 9% 8% 1	8640
February	1st to 10th	Night	66% 6% 11% 12% 5%	2730
	11th to 20th	Night	59% 6% 11% 17% 7%	2656
	21st to end	Night	59% 6% 11% 16% 7% 1	2076
March	1st to 10th	Night	58% 4 8% 16% 10% 3	5411
	11th to 20th	Night	51% 6% 17% 16% 8% 3	5090
	21st to end	Night	55% 5% 7% 19% 12% 2	5316
April	1st to 10th	Night	52% 5% 10% 20% 12% 1	2100
	11th to 20th	Night	51% 6% 10% 18% 15% 1	2075
	21st to end	Night	51% 6% 8% 18% 15% 3	2034
May	1st to 10th	Night	60% 7% 9% 14% 8% 3	3608
	11th to 20th	Night	46% 9% 14% 18% 12% 1	3576
	21st to end	Night	49% 7% 10% 19% 14% 1	3927
June	1st to 10th	Night	46% 9% 12% 21% 11% 1	1600
	11th to 20th	Night	40% 8% 12% 22% 16% 2	1600
	21st to end	Night	45% 8% 12% 23% 12% 1	1600
July	1st to 10th	Night	41% 6% 16% 22% 14% 1	3560
	11th to 20th	Night	39% 5% 13% 31% 11% 1	3552
	21st to end	Night	34% 7% 12% 32% 14% 1	3809
August	1st to 10th	Night	40% 7% 16% 24% 12% 1	2760
	11th to 20th	Night	41% 7% 13% 29% 10% 1	2930
	21st to end	Night	37% 7% 15% 31% 10% 1	3586
September	1st to 10th	Night	37% 7% 14% 28% 13% 1	2000
	11th to 20th	Night	33% 6% 14% 30% 16% 1	2000
	21st to end	Night	41% 7% 12% 26% 13% 1	2269
October	1st to 10th	Night	43% 5% 12% 26% 13% 1	3920
	11th to 20th	Night	45% 6% 15% 24% 10%	3899
	21st to end	Night	52% 5% 13% 21% 7%	4446
November	1st to 10th	Night	50% 5% 14% 19% 9% 1	2667
	11th to 20th	Night	52% 7% 13% 18% 8% 2	2909
	21st to end	Night	63% 8% 12% 13% 4	2940
December	1st to 10th	Night	72% 7% 10% 9% 2	4720
	11th to 20th	Night	64% 5% 10% 14% 8%	5348
	21st to end	Night	67% 6% 9% 11% 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	26% 21% 32% 15% 6%	220
	11th to 20th	Day	34% 20% 30% 14% 2	220
	21st to end	Day	25% 22% 31% 18% 4	319
February	1st to 10th	Day	30% 24% 31% 13% 2	330
	11th to 20th	Day	31% 25% 33% 11% 1	337
	21st to end	Day	33% 20% 30% 15% 1	446
March	1st to 10th	Day	29% 16% 32% 17% 6%	540
	11th to 20th	Day	30% 20% 27% 18% 4	540
	21st to end	Day	33% 18% 28% 14% 5% 1	594
April	1st to 10th	Day	30% 22% 28% 14% 6%	540
	11th to 20th	Day	28% 23% 24% 16% 5% 3	532
	21st to end	Day	30% 16% 32% 14% 7% 2	540
May	1st to 10th	Day	25% 15% 32% 17% 9% 2	507
	11th to 20th	Day	17% 14% 34% 23% 10% 3	527
	21st to end	Day	21% 11% 31% 22% 12% 2	573
June	1st to 10th	Day	22% 12% 34% 21% 9% 2	530
	11th to 20th	Day	19% 15% 31% 22% 11% 3	530
	21st to end	Day	20% 14% 33% 22% 9% 2	530
July	1st to 10th	Day	13% 11% 28% 29% 16% 3	525
	11th to 20th	Day	15% 9% 29% 30% 14% 3	524
	21st to end	Day	11% 12% 34% 30% 11% 1	576
August	1st to 10th	Day	12% 9% 30% 29% 17% 3	526
	11th to 20th	Day	15% 9% 24% 30% 16% 7%	519
	21st to end	Day	16% 10% 32% 22% 15% 5%	583
September	1st to 10th	Day	17% 9% 29% 27% 12% 6%	530
	11th to 20th	Day	10% 7% 26% 26% 20% 11%	530
	21st to end	Day	21% 11% 25% 26% 15% 3	530
October	1st to 10th	Day	25% 14% 24% 19% 12% 5%	530
	11th to 20th	Day	24% 21% 30% 16% 7% 2	530
	21st to end	Day	33% 15% 28% 20% 4	517
November	1st to 10th	Day	28% 20% 29% 16% 6%	425
	11th to 20th	Day	27% 20% 33% 11% 7% 1	246
	21st to end	Day	32% 21% 33% 10% 3	220
December	1st to 10th	Day	37% 15% 30% 16% 3	220
	11th to 20th	Day	35% 23% 30% 10% 3	220
	21st to end	Day	33% 20% 26% 17% 5%	242
January	1st to 10th	Night	31% 19% 28% 17% 4	840
	11th to 20th	Night	31% 18% 28% 18% 4	840
	21st to end	Night	25% 16% 30% 23% 6%	924
February	1st to 10th	Night	25% 21% 32% 19% 3	840
	11th to 20th	Night	25% 17% 35% 19% 3	823
	21st to end	Night	28% 16% 33% 20% 2	692
March	1st to 10th	Night	28% 15% 31% 23% 4	840
	11th to 20th	Night	28% 17% 28% 22% 4 1	840
	21st to end	Night	26% 14% 32% 21% 7%	924
April	1st to 10th	Night	27% 15% 32% 23% 3	840
	11th to 20th	Night	26% 17% 30% 21% 6%	831
	21st to end	Night	27% 12% 29% 23% 9% 1	774
May	1st to 10th	Night	26% 10% 26% 27% 9% 2	402
	11th to 20th	Night	16% 9% 32% 35% 7% 1	394
	21st to end	Night	14% 10% 32% 30% 13% 1	433
June	1st to 10th	Night	21% 7% 28% 35% 9% 1	400
	11th to 20th	Night	15% 10% 28% 33% 14% 1	400
	21st to end	Night	18% 8% 29% 33% 13%	400
July	1st to 10th	Night	12% 4 31% 35% 16% 1	390
	11th to 20th	Night	11% 6% 23% 38% 21% 2	388
	21st to end	Night	14% 5% 26% 41% 12% 1	438
August	1st to 10th	Night	14% 3 24% 36% 22% 1	504
	11th to 20th	Night	16% 5% 20% 32% 23% 4	609
	21st to end	Night	13% 6% 28% 34% 18% 2	880
September	1st to 10th	Night	16% 7% 25% 32% 18% 2	800
	11th to 20th	Night	15% 6% 20% 30% 25% 5%	800
	21st to end	Night	17% 10% 25% 27% 19% 2	800
October	1st to 10th	Night	25% 12% 26% 19% 17% 2	800
	11th to 20th	Night	25% 13% 28% 24% 9% 1	800
	21st to end	Night	32% 12% 30% 21% 5%	880
November	1st to 10th	Night	28% 15% 29% 20% 8%	820
	11th to 20th	Night	26% 18% 30% 18% 8%	840
	21st to end	Night	33% 19% 26% 16% 6%	840
December	1st to 10th	Night	33% 19% 26% 17% 4	840
	11th to 20th	Night	31% 19% 31% 16% 2 1	840
	21st to end	Night	35% 17% 29% 16% 3	924

Page generated at 2026-04-29 02:21:43. Version ac07

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