Campbellford
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Campbellford 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	15% 10% 3 8% 5% 5% 5% 4 5% 7% 34%	132082
	Night	15% 10% 4 8% 5% 5% 5% 4 5% 7% 34%	130393
Transparency	Day	48% 6% 12% 21% 12% 1	135636
	Night	48% 7% 12% 20% 12% 1	134925
Seeing	Day	22% 17% 31% 19% 9% 3	16264
	Night	20% 14% 31% 25% 10% 1	25655

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	16% 12% 4 9% 5% 4 5% 3 6% 7% 30%	4661
	11th to 20th	Day	10% 20% 7% 15% 8% 6% 4 3 4 4 18%	4692
	21st to end	Day	12% 15% 7% 13% 8% 7% 5% 4 5% 5% 20%	5780
February	1st to 10th	Day	14% 14% 5% 10% 6% 6% 5% 4 5% 5% 25%	1890
	11th to 20th	Day	12% 13% 5% 13% 7% 6% 5% 3 4 5% 27%	1843
	21st to end	Day	19% 14% 5% 9% 6% 6% 4 3 4 5% 25%	1653
March	1st to 10th	Day	19% 12% 4 9% 4 4 4 3 4 5% 31%	4894
	11th to 20th	Day	11% 13% 4 9% 5% 5% 5% 4 5% 7% 31%	5090
	21st to end	Day	18% 10% 3 6% 4 3 3 3 4 5% 40%	5679
April	1st to 10th	Day	20% 12% 4 7% 6% 4 4 3 4 5% 32%	2520
	11th to 20th	Day	22% 9% 2 5% 4 4 3 3 4 6% 37%	2494
	21st to end	Day	21% 8% 3 7% 5% 4 5% 3 5% 5% 34%	2710
May	1st to 10th	Day	21% 8% 3 8% 5% 5% 4 3 5% 6% 31%	6167
	11th to 20th	Day	17% 9% 4 8% 5% 4 4 4 5% 6% 35%	6318
	21st to end	Day	19% 7% 2 6% 4 4 4 4 5% 8% 36%	6949
June	1st to 10th	Day	17% 7% 3 7% 5% 5% 5% 5% 5% 8% 33%	2800
	11th to 20th	Day	13% 6% 2 6% 4 5% 5% 4 7% 9% 39%	2800
	21st to end	Day	16% 7% 3 7% 5% 4 5% 4 6% 9% 36%	2800
July	1st to 10th	Day	10% 6% 2 6% 5% 5% 5% 4 7% 9% 41%	6360
	11th to 20th	Day	10% 4 2 5% 4 4 5% 4 6% 9% 47%	6360
	21st to end	Day	6% 4 2 6% 4 5% 5% 4 7% 9% 47%	6845
August	1st to 10th	Day	15% 8% 2 6% 4 4 4 4 6% 8% 39%	4234
	11th to 20th	Day	14% 6% 3 7% 4 4 5% 4 6% 10% 37%	4174
	21st to end	Day	10% 5% 2 5% 5% 5% 5% 4 7% 9% 42%	4383
September	1st to 10th	Day	12% 5% 2 6% 4 5% 5% 4 5% 9% 43%	2400
	11th to 20th	Day	10% 5% 2 5% 4 4 4 4 6% 7% 51%	2400
	21st to end	Day	15% 6% 3 7% 4 4 5% 4 5% 7% 41%	2086
October	1st to 10th	Day	17% 7% 3 7% 4 4 4 4 5% 7% 37%	2000
	11th to 20th	Day	19% 9% 3 8% 6% 5% 4 4 4 7% 31%	2000
	21st to end	Day	23% 10% 3 8% 5% 5% 4 4 4 6% 27%	2169
November	1st to 10th	Day	15% 10% 3 6% 5% 5% 4 4 6% 7% 35%	1777
	11th to 20th	Day	14% 12% 4 9% 5% 4 4 4 5% 8% 31%	1680
	21st to end	Day	20% 13% 4 8% 5% 5% 5% 4 4 6% 24%	1680
December	1st to 10th	Day	17% 16% 5% 11% 6% 5% 5% 3 4 7% 20%	2680
	11th to 20th	Day	16% 18% 5% 10% 5% 4 4 3 4 4 27%	3066
	21st to end	Day	24% 14% 4 9% 5% 4 4 3 4 5% 23%	4048
January	1st to 10th	Night	14% 14% 6% 12% 6% 5% 5% 4 5% 6% 23%	8234
	11th to 20th	Night	12% 16% 6% 15% 7% 6% 5% 4 5% 6% 18%	8175
	21st to end	Night	12% 13% 6% 11% 6% 5% 5% 3 5% 6% 28%	8401
February	1st to 10th	Night	12% 15% 4 10% 7% 5% 5% 4 5% 6% 28%	2730
	11th to 20th	Night	13% 13% 5% 10% 6% 5% 6% 4 5% 6% 28%	2663
	21st to end	Night	15% 11% 4 9% 5% 5% 5% 4 5% 7% 31%	2152
March	1st to 10th	Night	17% 11% 4 9% 6% 5% 4 4 5% 6% 31%	5164
	11th to 20th	Night	11% 10% 4 8% 5% 5% 5% 4 6% 8% 34%	5089
	21st to end	Night	19% 8% 3 5% 4 3 4 3 5% 6% 40%	5495
April	1st to 10th	Night	20% 9% 3 7% 5% 4 4 3 4 6% 35%	2100
	11th to 20th	Night	18% 8% 2 7% 4 4 3 4 5% 7% 38%	2075
	21st to end	Night	17% 6% 3 7% 4 5% 5% 5% 6% 7% 35%	1927
May	1st to 10th	Night	25% 8% 3 6% 4 4 5% 3 5% 5% 31%	3796
	11th to 20th	Night	14% 7% 2 7% 4 4 4 4 5% 7% 41%	3575
	21st to end	Night	17% 7% 3 7% 4 4 4 3 5% 7% 39%	3926
June	1st to 10th	Night	14% 5% 3 7% 6% 5% 5% 4 6% 9% 38%	1600
	11th to 20th	Night	10% 6% 2 6% 4 5% 5% 4 7% 7% 45%	1600
	21st to end	Night	13% 7% 2 7% 4 5% 4 4 5% 7% 42%	1600
July	1st to 10th	Night	8% 6% 2 6% 5% 5% 5% 4 7% 9% 43%	3600
	11th to 20th	Night	9% 5% 2 5% 4 4 4 3 6% 7% 50%	3600
	21st to end	Night	9% 4 2 5% 4 3 4 4 5% 9% 52%	4004
August	1st to 10th	Night	10% 5% 2 6% 4 4 4 3 6% 8% 47%	2915
	11th to 20th	Night	13% 6% 2 5% 3 3 4 3 5% 9% 47%	2875
	21st to end	Night	8% 5% 2 5% 4 4 5% 4 6% 9% 49%	3482
September	1st to 10th	Night	10% 6% 2 6% 4 4 3 4 6% 7% 48%	2000
	11th to 20th	Night	11% 4 1 5% 3 4 4 3 6% 7% 54%	2000
	21st to end	Night	17% 7% 3 6% 4 4 4 3 4 5% 44%	2310
October	1st to 10th	Night	16% 7% 2 6% 4 4 4 3 5% 7% 41%	2400
	11th to 20th	Night	20% 8% 3 8% 5% 4 4 3 4 6% 34%	2400
	21st to end	Night	20% 10% 3 7% 5% 5% 5% 3 5% 6% 31%	2670
November	1st to 10th	Night	17% 9% 2 6% 4 4 4 4 5% 6% 38%	2737
	11th to 20th	Night	16% 10% 3 7% 6% 5% 5% 4 5% 8% 31%	2940
	21st to end	Night	19% 11% 3 8% 5% 5% 5% 4 6% 6% 27%	2940
December	1st to 10th	Night	17% 15% 4 8% 5% 4 4 5% 7% 8% 22%	4720
	11th to 20th	Night	17% 14% 4 10% 4 5% 4 3 5% 7% 26%	5348
	21st to end	Night	25% 15% 4 11% 5% 4 4 3 4 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	53% 6% 14% 18% 8% 1	4662
	11th to 20th	Day	69% 6% 7% 10% 8% 1	4722
	21st to end	Day	64% 6% 9% 11% 9% 1	5780
February	1st to 10th	Day	59% 7% 10% 16% 6% 1	1890
	11th to 20th	Day	58% 6% 11% 14% 10% 1	1852
	21st to end	Day	61% 6% 10% 14% 9% 1	1653
March	1st to 10th	Day	53% 6% 12% 14% 14% 1	4897
	11th to 20th	Day	50% 5% 20% 14% 9% 2	5090
	21st to end	Day	47% 5% 7% 21% 17% 2	5679
April	1st to 10th	Day	53% 6% 9% 18% 11% 2	2520
	11th to 20th	Day	49% 4 11% 20% 15% 1	2494
	21st to end	Day	51% 6% 9% 18% 12% 2	2710
May	1st to 10th	Day	52% 6% 10% 17% 11% 3	6176
	11th to 20th	Day	49% 7% 11% 16% 16% 1	6322
	21st to end	Day	46% 6% 13% 22% 11% 2	6949
June	1st to 10th	Day	46% 9% 13% 18% 14% 1	2800
	11th to 20th	Day	39% 8% 14% 24% 13% 1	2800
	21st to end	Day	43% 8% 14% 22% 12% 1	2800
July	1st to 10th	Day	38% 6% 15% 27% 14% 1	6290
	11th to 20th	Day	33% 6% 14% 30% 16%	6285
	21st to end	Day	31% 7% 14% 35% 12%	6648
August	1st to 10th	Day	43% 7% 15% 23% 12% 1	4221
	11th to 20th	Day	41% 6% 14% 28% 9%	4213
	21st to end	Day	36% 7% 13% 33% 10% 1	4383
September	1st to 10th	Day	37% 8% 14% 29% 12% 1	2400
	11th to 20th	Day	31% 7% 15% 31% 15% 1	2400
	21st to end	Day	42% 7% 15% 25% 10%	2086
October	1st to 10th	Day	39% 6% 13% 30% 12% 1	3260
	11th to 20th	Day	43% 6% 16% 23% 12% 1	3240
	21st to end	Day	50% 6% 14% 20% 9%	3483
November	1st to 10th	Day	47% 8% 15% 19% 10% 1	1777
	11th to 20th	Day	50% 8% 15% 15% 10% 1	1680
	21st to end	Day	59% 8% 13% 13% 7%	1680
December	1st to 10th	Day	64% 6% 15% 10% 5%	2680
	11th to 20th	Day	60% 7% 9% 14% 9%	3066
	21st to end	Day	64% 6% 8% 15% 8%	4048
January	1st to 10th	Night	59% 7% 12% 14% 8%	8234
	11th to 20th	Night	64% 9% 9% 11% 7% 1	8220
	21st to end	Night	55% 7% 9% 14% 14%	8401
February	1st to 10th	Night	56% 7% 12% 18% 6% 1	2730
	11th to 20th	Night	55% 7% 11% 19% 8% 1	2665
	21st to end	Night	51% 7% 13% 20% 9% 1	2152
March	1st to 10th	Night	54% 6% 8% 16% 12% 4	5174
	11th to 20th	Night	45% 7% 19% 19% 9% 1	5090
	21st to end	Night	44% 4 11% 22% 16% 2	5495
April	1st to 10th	Night	50% 5% 10% 20% 13% 2	2100
	11th to 20th	Night	46% 6% 12% 19% 16% 1	2075
	21st to end	Night	45% 8% 12% 18% 15% 2	1927
May	1st to 10th	Night	53% 6% 11% 14% 12% 4	3803
	11th to 20th	Night	41% 7% 15% 21% 15% 2	3576
	21st to end	Night	44% 7% 13% 20% 14% 2	3927
June	1st to 10th	Night	42% 7% 12% 23% 15% 2	1600
	11th to 20th	Night	36% 7% 13% 21% 20% 3	1600
	21st to end	Night	41% 6% 15% 23% 14% 2	1600
July	1st to 10th	Night	38% 5% 16% 22% 19% 1	3560
	11th to 20th	Night	33% 5% 14% 32% 16% 1	3552
	21st to end	Night	30% 6% 14% 35% 15% 1	3886
August	1st to 10th	Night	35% 6% 13% 29% 16% 1	2904
	11th to 20th	Night	35% 5% 19% 27% 13% 1	2902
	21st to end	Night	31% 7% 13% 36% 12% 1	3482
September	1st to 10th	Night	34% 8% 15% 28% 14% 1	2000
	11th to 20th	Night	29% 7% 14% 33% 17% 1	2000
	21st to end	Night	42% 7% 11% 27% 13% 1	2310
October	1st to 10th	Night	34% 6% 10% 29% 21% 1	3920
	11th to 20th	Night	42% 5% 15% 29% 9%	3899
	21st to end	Night	45% 6% 14% 26% 10%	4306
November	1st to 10th	Night	45% 7% 14% 23% 11% 1	2737
	11th to 20th	Night	49% 9% 13% 18% 9% 2	2940
	21st to end	Night	54% 10% 15% 16% 5%	2940
December	1st to 10th	Night	57% 7% 16% 16% 4	4720
	11th to 20th	Night	57% 8% 11% 13% 9% 1	5348
	21st to end	Night	66% 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	23% 24% 34% 15% 3 1	220
	11th to 20th	Day	28% 25% 27% 16% 3 1	228
	21st to end	Day	26% 25% 30% 14% 4 1	363
February	1st to 10th	Day	31% 24% 29% 13% 3 1	330
	11th to 20th	Day	29% 26% 35% 8%	330
	21st to end	Day	33% 23% 36% 9%	369
March	1st to 10th	Day	25% 22% 35% 15% 3	540
	11th to 20th	Day	30% 22% 31% 14% 3	540
	21st to end	Day	34% 17% 32% 12% 5% 1	594
April	1st to 10th	Day	29% 23% 33% 10% 5%	540
	11th to 20th	Day	34% 20% 23% 14% 7% 2	532
	21st to end	Day	27% 21% 31% 14% 5% 1	540
May	1st to 10th	Day	22% 19% 32% 18% 5% 4	507
	11th to 20th	Day	19% 15% 35% 20% 8% 3	527
	21st to end	Day	17% 13% 35% 20% 12% 3	573
June	1st to 10th	Day	18% 15% 35% 23% 7% 2	530
	11th to 20th	Day	14% 15% 32% 24% 12% 2	530
	21st to end	Day	21% 12% 32% 24% 9% 3	530
July	1st to 10th	Day	10% 10% 32% 29% 15% 3	525
	11th to 20th	Day	15% 8% 30% 26% 16% 4	524
	21st to end	Day	8% 10% 37% 28% 13% 4	576
August	1st to 10th	Day	10% 8% 30% 30% 15% 6%	526
	11th to 20th	Day	14% 6% 28% 29% 17% 7%	519
	21st to end	Day	13% 11% 31% 25% 14% 7%	583
September	1st to 10th	Day	12% 11% 31% 25% 13% 8%	530
	11th to 20th	Day	10% 8% 23% 26% 20% 12%	530
	21st to end	Day	17% 14% 27% 25% 12% 5%	530
October	1st to 10th	Day	20% 19% 23% 18% 14% 6%	530
	11th to 20th	Day	23% 21% 31% 16% 7% 2	530
	21st to end	Day	29% 19% 28% 19% 4	565
November	1st to 10th	Day	27% 19% 26% 17% 9% 1	351
	11th to 20th	Day	25% 23% 34% 13% 5%	220
	21st to end	Day	26% 25% 32% 13% 4	220
December	1st to 10th	Day	30% 18% 33% 14% 5%	220
	11th to 20th	Day	33% 23% 30% 11% 2	220
	21st to end	Day	37% 19% 32% 10% 2	242
January	1st to 10th	Night	24% 22% 33% 17% 4	840
	11th to 20th	Night	26% 19% 32% 19% 5%	840
	21st to end	Night	20% 17% 35% 22% 5%	924
February	1st to 10th	Night	21% 20% 38% 19% 2	840
	11th to 20th	Night	23% 19% 37% 17% 4	823
	21st to end	Night	23% 20% 36% 18% 3	692
March	1st to 10th	Night	21% 19% 36% 20% 3	840
	11th to 20th	Night	25% 17% 34% 20% 4 1	840
	21st to end	Night	22% 16% 34% 22% 6% 1	924
April	1st to 10th	Night	23% 17% 35% 22% 3	840
	11th to 20th	Night	23% 17% 32% 21% 7% 1	831
	21st to end	Night	21% 12% 31% 27% 9% 1	667
May	1st to 10th	Night	22% 9% 30% 28% 10% 1	493
	11th to 20th	Night	14% 9% 36% 32% 9%	394
	21st to end	Night	13% 6% 33% 33% 13% 1	433
June	1st to 10th	Night	13% 7% 36% 31% 12% 1	400
	11th to 20th	Night	11% 9% 30% 34% 15% 1	400
	21st to end	Night	14% 8% 29% 35% 14% 1	400
July	1st to 10th	Night	6% 6% 30% 43% 15% 1	390
	11th to 20th	Night	10% 3 28% 36% 22% 1	388
	21st to end	Night	10% 3 30% 40% 17% 1	466
August	1st to 10th	Night	10% 4 21% 37% 27% 2	597
	11th to 20th	Night	9% 7% 21% 36% 25% 3	594
	21st to end	Night	10% 5% 28% 35% 19% 2	815
September	1st to 10th	Night	11% 6% 29% 32% 20% 2	800
	11th to 20th	Night	12% 5% 21% 31% 28% 4	800
	21st to end	Night	18% 9% 24% 27% 19% 3	800
October	1st to 10th	Night	20% 9% 28% 25% 16% 2	800
	11th to 20th	Night	22% 15% 31% 23% 8% 1	800
	21st to end	Night	25% 14% 34% 23% 5%	880
November	1st to 10th	Night	24% 14% 25% 27% 8% 1	820
	11th to 20th	Night	22% 18% 34% 20% 6% 1	840
	21st to end	Night	27% 16% 31% 20% 6%	840
December	1st to 10th	Night	27% 19% 31% 19% 3	840
	11th to 20th	Night	26% 19% 35% 17% 3	840
	21st to end	Night	32% 16% 33% 16% 3	924

Page generated at 2026-04-29 02:21:47. Version ac07

Copyright © 2026 Attilla Danko.