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 2025-01-07.

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 7% 5% 5% 4 4 5% 7% 35%	105152
	Night	16% 10% 3 8% 5% 4 4 4 5% 7% 34%	103876
Transparency	Day	47% 7% 13% 21% 11% 1	108724
	Night	47% 7% 13% 21% 11% 1	108392
Seeing	Day	21% 17% 31% 20% 9% 3	14596
	Night	20% 13% 31% 25% 10% 1	23954

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% 15% 4 9% 4 3 4 2 5% 5% 31%	2565
	11th to 20th	Day	12% 17% 6% 14% 8% 6% 5% 3 4 4 21%	2534
	21st to end	Day	20% 19% 6% 12% 6% 5% 3 3 4 3 20%	3124
February	1st to 10th	Day	14% 15% 5% 10% 7% 6% 5% 4 5% 5% 24%	1710
	11th to 20th	Day	11% 14% 5% 13% 6% 6% 4 3 4 6% 28%	1663
	21st to end	Day	19% 13% 5% 9% 6% 5% 5% 3 4 5% 26%	1499
March	1st to 10th	Day	20% 13% 3 8% 5% 4 4 3 4 6% 31%	3330
	11th to 20th	Day	11% 15% 4 9% 5% 4 5% 4 4 6% 32%	3480
	21st to end	Day	14% 8% 3 6% 4 3 3 3 5% 6% 46%	3878
April	1st to 10th	Day	20% 12% 3 6% 6% 4 4 3 4 5% 32%	2280
	11th to 20th	Day	22% 9% 2 5% 4 4 3 2 4 6% 38%	2254
	21st to end	Day	21% 8% 3 8% 5% 4 5% 3 4 5% 34%	2452
May	1st to 10th	Day	19% 7% 3 7% 4 5% 4 3 5% 7% 34%	4290
	11th to 20th	Day	16% 10% 3 7% 5% 4 4 4 7% 7% 33%	4398
	21st to end	Day	12% 5% 2 5% 4 5% 5% 4 6% 8% 43%	4837
June	1st to 10th	Day	17% 7% 3 7% 5% 4 5% 5% 6% 8% 33%	2660
	11th to 20th	Day	13% 6% 2 6% 4 5% 5% 4 7% 9% 39%	2660
	21st to end	Day	16% 7% 3 7% 5% 4 5% 4 6% 9% 36%	2660
July	1st to 10th	Day	11% 5% 2 6% 5% 5% 5% 4 8% 10% 39%	4440
	11th to 20th	Day	11% 5% 2 4 4 4 6% 4 6% 9% 45%	4440
	21st to end	Day	7% 4 2 7% 5% 5% 6% 5% 7% 9% 43%	4761
August	1st to 10th	Day	15% 8% 3 6% 4 4 4 4 6% 7% 38%	4104
	11th to 20th	Day	13% 6% 3 7% 4 4 5% 4 6% 10% 36%	4044
	21st to end	Day	11% 5% 2 5% 5% 5% 5% 5% 7% 9% 41%	4249
September	1st to 10th	Day	13% 5% 2 6% 4 5% 5% 4 5% 9% 42%	2280
	11th to 20th	Day	10% 5% 2 5% 4 4 4 4 6% 7% 50%	2280
	21st to end	Day	15% 7% 3 7% 4 4 4 4 5% 7% 41%	1982
October	1st to 10th	Day	18% 8% 3 8% 4 4 4 4 5% 7% 35%	1900
	11th to 20th	Day	20% 9% 3 8% 5% 5% 4 4 4 7% 31%	1900
	21st to end	Day	24% 10% 3 8% 5% 5% 4 4 4 6% 26%	2061
November	1st to 10th	Day	14% 10% 3 6% 5% 5% 5% 4 6% 7% 35%	1691
	11th to 20th	Day	15% 11% 4 9% 5% 4 4 4 6% 8% 31%	1600
	21st to end	Day	21% 13% 4 8% 5% 5% 5% 4 5% 6% 24%	1600
December	1st to 10th	Day	17% 16% 5% 11% 6% 5% 5% 3 4 7% 20%	2600
	11th to 20th	Day	16% 18% 5% 10% 5% 4 4 3 4 4 27%	2986
	21st to end	Day	24% 14% 4 9% 5% 4 4 3 4 5% 23%	3960
January	1st to 10th	Night	18% 14% 5% 10% 5% 5% 6% 4 5% 5% 23%	4514
	11th to 20th	Night	14% 12% 6% 13% 7% 6% 5% 3 5% 5% 23%	4408
	21st to end	Night	19% 15% 7% 10% 5% 4 4 3 4 5% 23%	4532
February	1st to 10th	Night	13% 15% 4 10% 7% 5% 5% 4 5% 6% 26%	2470
	11th to 20th	Night	13% 13% 5% 9% 5% 5% 5% 4 6% 6% 29%	2403
	21st to end	Night	15% 11% 4 9% 4 4 4 4 5% 7% 32%	1954
March	1st to 10th	Night	19% 10% 4 9% 5% 4 4 4 5% 6% 32%	3509
	11th to 20th	Night	15% 12% 5% 9% 5% 5% 5% 4 5% 6% 30%	3479
	21st to end	Night	16% 7% 2 5% 4 3 3 3 4 6% 46%	3754
April	1st to 10th	Night	20% 9% 3 6% 5% 4 4 3 4 6% 36%	1900
	11th to 20th	Night	18% 8% 3 7% 4 4 4 4 5% 6% 38%	1875
	21st to end	Night	18% 7% 3 7% 4 5% 4 5% 6% 7% 34%	1743
May	1st to 10th	Night	21% 7% 4 6% 4 5% 5% 3 5% 6% 36%	2651
	11th to 20th	Night	16% 8% 2 7% 4 4 5% 4 6% 7% 37%	2495
	21st to end	Night	10% 6% 2 6% 4 4 4 3 5% 8% 47%	2738
June	1st to 10th	Night	14% 5% 3 7% 6% 5% 5% 4 6% 9% 38%	1520
	11th to 20th	Night	10% 6% 2 5% 4 5% 5% 4 7% 7% 45%	1520
	21st to end	Night	13% 7% 2 7% 4 5% 4 4 5% 7% 41%	1520
July	1st to 10th	Night	8% 5% 2 6% 6% 5% 5% 4 7% 7% 45%	2520
	11th to 20th	Night	11% 5% 2 5% 4 3 4 3 6% 7% 49%	2520
	21st to end	Night	9% 4 1 5% 4 4 4 4 5% 8% 51%	2789
August	1st to 10th	Night	11% 5% 2 6% 4 4 4 3 6% 8% 47%	2825
	11th to 20th	Night	14% 6% 2 5% 3 3 4 3 5% 9% 47%	2785
	21st to end	Night	8% 5% 2 5% 4 4 4 4 6% 9% 49%	3375
September	1st to 10th	Night	11% 6% 2 6% 4 4 3 4 6% 8% 47%	1900
	11th to 20th	Night	11% 4 2 5% 3 4 3 3 6% 7% 53%	1900
	21st to end	Night	16% 7% 2 6% 4 4 5% 3 4 5% 44%	2194
October	1st to 10th	Night	17% 7% 2 6% 5% 4 4 3 5% 6% 40%	2280
	11th to 20th	Night	20% 8% 3 8% 5% 4 4 3 4 6% 34%	2280
	21st to end	Night	21% 10% 3 7% 5% 5% 5% 3 5% 6% 30%	2536
November	1st to 10th	Night	18% 9% 2 6% 4 4 4 4 5% 6% 39%	2603
	11th to 20th	Night	17% 10% 3 7% 6% 5% 5% 4 5% 8% 31%	2800
	21st to end	Night	20% 11% 3 8% 5% 5% 5% 5% 6% 6% 27%	2800
December	1st to 10th	Night	18% 15% 4 8% 5% 4 4 5% 7% 8% 22%	4580
	11th to 20th	Night	18% 15% 4 10% 4 5% 4 3 5% 7% 26%	5208
	21st to end	Night	25% 15% 4 11% 5% 4 4 3 4 5% 20%	6996

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	54% 8% 16% 14% 7% 2	2566
	11th to 20th	Day	65% 7% 10% 10% 7%	2534
	21st to end	Day	68% 7% 9% 10% 5% 1	3124
February	1st to 10th	Day	60% 8% 11% 15% 5% 1	1710
	11th to 20th	Day	57% 6% 11% 14% 10% 1	1672
	21st to end	Day	60% 6% 11% 13% 9% 1	1499
March	1st to 10th	Day	53% 7% 13% 17% 9% 1	3333
	11th to 20th	Day	50% 8% 17% 15% 9% 2	3480
	21st to end	Day	39% 6% 10% 26% 17% 3	3878
April	1st to 10th	Day	53% 6% 9% 19% 11% 2	2280
	11th to 20th	Day	47% 4 11% 21% 15% 1	2254
	21st to end	Day	51% 7% 10% 17% 13% 2	2452
May	1st to 10th	Day	47% 8% 11% 20% 12% 2	4302
	11th to 20th	Day	47% 9% 14% 20% 10% 1	4402
	21st to end	Day	36% 8% 14% 24% 15% 3	4837
June	1st to 10th	Day	46% 9% 13% 17% 13% 1	2660
	11th to 20th	Day	39% 8% 14% 23% 13% 1	2660
	21st to end	Day	43% 8% 13% 22% 12% 1	2660
July	1st to 10th	Day	37% 7% 16% 26% 14% 1	4370
	11th to 20th	Day	33% 7% 16% 34% 10%	4365
	21st to end	Day	34% 9% 15% 29% 13%	4609
August	1st to 10th	Day	44% 7% 15% 22% 12% 1	4091
	11th to 20th	Day	41% 7% 15% 28% 9%	4083
	21st to end	Day	36% 7% 13% 32% 10% 1	4249
September	1st to 10th	Day	37% 8% 15% 28% 12% 1	2280
	11th to 20th	Day	32% 7% 15% 30% 15% 1	2280
	21st to end	Day	42% 7% 15% 26% 9%	1982
October	1st to 10th	Day	40% 6% 13% 30% 11% 1	3160
	11th to 20th	Day	43% 6% 16% 23% 11% 1	3140
	21st to end	Day	50% 6% 15% 20% 9%	3375
November	1st to 10th	Day	47% 8% 16% 19% 10% 1	1691
	11th to 20th	Day	50% 9% 15% 15% 10% 1	1600
	21st to end	Day	59% 8% 13% 13% 7%	1600
December	1st to 10th	Day	64% 6% 15% 10% 4	2600
	11th to 20th	Day	60% 7% 9% 14% 9%	2986
	21st to end	Day	64% 6% 8% 15% 8%	3960
January	1st to 10th	Night	60% 9% 14% 12% 4	4514
	11th to 20th	Night	59% 11% 12% 12% 4 1	4408
	21st to end	Night	63% 8% 11% 12% 6%	4532
February	1st to 10th	Night	58% 7% 13% 17% 5% 1	2470
	11th to 20th	Night	54% 7% 11% 19% 8%	2405
	21st to end	Night	50% 7% 14% 19% 9% 1	1954
March	1st to 10th	Night	52% 7% 10% 20% 10% 1	3519
	11th to 20th	Night	50% 8% 16% 16% 8% 1	3480
	21st to end	Night	37% 5% 12% 25% 18% 2	3754
April	1st to 10th	Night	49% 5% 10% 20% 13% 2	1900
	11th to 20th	Night	46% 6% 12% 18% 17% 2	1875
	21st to end	Night	45% 9% 13% 16% 15% 2	1743
May	1st to 10th	Night	47% 8% 13% 16% 14% 2	2658
	11th to 20th	Night	43% 9% 14% 22% 10% 2	2496
	21st to end	Night	34% 9% 13% 22% 20% 2	2739
June	1st to 10th	Night	42% 7% 12% 23% 14% 2	1520
	11th to 20th	Night	35% 8% 13% 21% 20% 3	1520
	21st to end	Night	41% 7% 15% 22% 14% 2	1520
July	1st to 10th	Night	36% 5% 14% 24% 19% 1	2480
	11th to 20th	Night	34% 5% 14% 33% 14%	2472
	21st to end	Night	31% 6% 17% 33% 12% 1	2700
August	1st to 10th	Night	36% 6% 13% 29% 15% 1	2814
	11th to 20th	Night	35% 5% 19% 27% 12% 1	2812
	21st to end	Night	31% 7% 13% 36% 12% 1	3375
September	1st to 10th	Night	35% 8% 16% 26% 14% 1	1900
	11th to 20th	Night	30% 7% 14% 31% 17% 1	1900
	21st to end	Night	41% 7% 11% 27% 12% 1	2194
October	1st to 10th	Night	35% 6% 10% 28% 20% 1	3800
	11th to 20th	Night	42% 5% 15% 29% 9%	3779
	21st to end	Night	45% 6% 14% 25% 9%	4172
November	1st to 10th	Night	45% 7% 14% 23% 11% 1	2603
	11th to 20th	Night	49% 9% 13% 18% 9% 2	2800
	21st to end	Night	53% 10% 15% 16% 5%	2800
December	1st to 10th	Night	58% 7% 16% 16% 4	4580
	11th to 20th	Night	58% 8% 11% 13% 9% 1	5208
	21st to end	Night	66% 7% 8% 11% 8%	6996

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% 33% 15% 4 1	192
	11th to 20th	Day	26% 25% 30% 16% 3 1	186
	21st to end	Day	27% 23% 30% 14% 4 1	297
February	1st to 10th	Day	30% 26% 30% 11% 2	270
	11th to 20th	Day	27% 28% 37% 8%	270
	21st to end	Day	34% 23% 34% 9%	311
March	1st to 10th	Day	23% 22% 36% 15% 4	460
	11th to 20th	Day	26% 23% 32% 15% 3	460
	21st to end	Day	32% 17% 32% 13% 5% 1	506
April	1st to 10th	Day	27% 21% 35% 11% 6%	460
	11th to 20th	Day	31% 21% 23% 15% 8% 3	452
	21st to end	Day	27% 22% 31% 13% 5% 2	460
May	1st to 10th	Day	22% 18% 31% 19% 6% 4	463
	11th to 20th	Day	19% 15% 34% 21% 9% 3	487
	21st to end	Day	15% 13% 36% 20% 12% 4	529
June	1st to 10th	Day	18% 14% 35% 24% 7% 2	490
	11th to 20th	Day	14% 15% 31% 24% 13% 3	490
	21st to end	Day	21% 12% 32% 24% 9% 3	490
July	1st to 10th	Day	10% 10% 32% 29% 15% 4	485
	11th to 20th	Day	15% 9% 30% 25% 16% 5%	484
	21st to end	Day	9% 10% 35% 29% 13% 4	532
August	1st to 10th	Day	10% 9% 31% 29% 15% 6%	486
	11th to 20th	Day	13% 6% 28% 28% 18% 6%	479
	21st to end	Day	12% 11% 31% 25% 14% 7%	539
September	1st to 10th	Day	12% 10% 32% 26% 12% 8%	490
	11th to 20th	Day	11% 9% 24% 25% 18% 13%	490
	21st to end	Day	16% 15% 27% 24% 13% 5%	490
October	1st to 10th	Day	21% 20% 23% 17% 13% 6%	490
	11th to 20th	Day	23% 21% 30% 16% 8% 2	490
	21st to end	Day	30% 19% 28% 19% 4	523
November	1st to 10th	Day	26% 19% 26% 19% 9% 1	325
	11th to 20th	Day	24% 23% 35% 15% 4 1	200
	21st to end	Day	26% 24% 32% 14% 5%	200
December	1st to 10th	Day	30% 19% 33% 14% 5%	200
	11th to 20th	Day	34% 23% 30% 12% 2 1	200
	21st to end	Day	35% 19% 32% 11% 2	220
January	1st to 10th	Night	25% 21% 32% 17% 4	785
	11th to 20th	Night	25% 18% 33% 19% 5%	760
	21st to end	Night	20% 16% 34% 23% 5%	836
February	1st to 10th	Night	21% 20% 38% 18% 2	760
	11th to 20th	Night	22% 19% 38% 17% 4	743
	21st to end	Night	23% 21% 35% 18% 4	628
March	1st to 10th	Night	20% 19% 37% 21% 4	760
	11th to 20th	Night	24% 17% 34% 20% 4 1	760
	21st to end	Night	20% 15% 34% 23% 7% 1	836
April	1st to 10th	Night	23% 16% 35% 23% 3	760
	11th to 20th	Night	22% 17% 32% 21% 8% 1	751
	21st to end	Night	21% 11% 32% 25% 10% 1	603
May	1st to 10th	Night	21% 9% 30% 27% 11% 2	466
	11th to 20th	Night	14% 9% 36% 32% 10%	374
	21st to end	Night	12% 6% 33% 34% 14% 1	411
June	1st to 10th	Night	13% 7% 36% 31% 13% 1	380
	11th to 20th	Night	10% 9% 30% 35% 15% 1	380
	21st to end	Night	14% 8% 28% 36% 14% 1	380
July	1st to 10th	Night	6% 5% 29% 43% 16% 1	370
	11th to 20th	Night	10% 3 28% 36% 23% 1	368
	21st to end	Night	10% 2 29% 41% 17% 1	442
August	1st to 10th	Night	10% 4 22% 36% 26% 2	567
	11th to 20th	Night	9% 7% 21% 36% 25% 3	564
	21st to end	Night	10% 5% 28% 35% 20% 2	774
September	1st to 10th	Night	12% 6% 29% 31% 19% 2	760
	11th to 20th	Night	12% 5% 21% 30% 28% 4	760
	21st to end	Night	18% 9% 24% 27% 19% 3	760
October	1st to 10th	Night	21% 9% 28% 24% 16% 2	760
	11th to 20th	Night	22% 16% 30% 23% 9% 1	760
	21st to end	Night	26% 14% 33% 22% 5%	836
November	1st to 10th	Night	24% 14% 25% 28% 8% 1	780
	11th to 20th	Night	22% 17% 34% 20% 6% 1	800
	21st to end	Night	27% 16% 31% 20% 6%	800
December	1st to 10th	Night	27% 20% 31% 18% 3	800
	11th to 20th	Night	26% 19% 35% 18% 3	800
	21st to end	Night	32% 15% 34% 16% 3	880

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