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 2024-01-17.

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% 4 6% 6% 3 5% 5% 5% 7% 35%	74729
	Night	16% 9% 3 7% 6% 3 5% 5% 5% 7% 35%	75093
Transparency	Day	48% 8% 13% 19% 11% 1	74436
	Night	48% 7% 13% 20% 11% 1	74920
Seeing	Day	21% 16% 31% 20% 9% 3	13345
	Night	20% 13% 31% 25% 10% 1	22743

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% 8% 7% 3 5% 4 6% 6% 27%	1517
	11th to 20th	Day	16% 17% 5% 9% 7% 3 5% 4 5% 5% 24%	1502
	21st to end	Day	13% 13% 6% 12% 8% 4 6% 5% 5% 5% 25%	1782
February	1st to 10th	Day	15% 15% 5% 9% 8% 5% 6% 5% 5% 5% 22%	1620
	11th to 20th	Day	12% 13% 6% 11% 8% 4 4 4 4 6% 28%	1573
	21st to end	Day	20% 13% 5% 8% 7% 4 5% 4 3 5% 26%	1413
March	1st to 10th	Day	14% 11% 4 8% 8% 5% 5% 4 6% 5% 31%	1913
	11th to 20th	Day	15% 13% 4 7% 6% 4 4 4 4 5% 34%	1980
	21st to end	Day	19% 10% 4 6% 5% 3 3 4 4 5% 38%	2214
April	1st to 10th	Day	20% 11% 4 6% 6% 3 4 4 4 6% 33%	2160
	11th to 20th	Day	21% 8% 3 4 5% 3 4 3 4 6% 40%	2134
	21st to end	Day	21% 8% 3 7% 5% 3 5% 4 4 5% 34%	2322
May	1st to 10th	Day	17% 7% 3 6% 6% 3 5% 4 5% 7% 35%	2438
	11th to 20th	Day	14% 7% 3 5% 5% 3 4 5% 6% 7% 41%	2478
	21st to end	Day	13% 5% 2 5% 6% 3 5% 5% 5% 8% 42%	2725
June	1st to 10th	Day	17% 6% 4 6% 5% 3 5% 6% 6% 8% 35%	2520
	11th to 20th	Day	14% 6% 2 5% 4 3 5% 5% 7% 10% 40%	2520
	21st to end	Day	15% 7% 3 6% 5% 3 5% 5% 6% 9% 36%	2520
July	1st to 10th	Day	10% 4 2 4 5% 4 6% 6% 7% 8% 44%	2520
	11th to 20th	Day	11% 5% 2 5% 5% 4 7% 6% 6% 9% 40%	2520
	21st to end	Day	9% 5% 2 6% 6% 4 7% 7% 7% 9% 38%	2717
August	1st to 10th	Day	10% 6% 3 5% 6% 4 6% 6% 7% 9% 41%	2327
	11th to 20th	Day	10% 6% 3 6% 6% 4 6% 5% 7% 10% 38%	2303
	21st to end	Day	13% 5% 2 5% 5% 4 5% 5% 7% 9% 41%	2417
September	1st to 10th	Day	13% 5% 3 5% 5% 3 5% 5% 6% 9% 42%	2160
	11th to 20th	Day	11% 4 2 5% 4 3 4 5% 6% 7% 49%	2160
	21st to end	Day	15% 6% 3 6% 5% 3 5% 5% 5% 6% 41%	1878
October	1st to 10th	Day	19% 8% 3 7% 5% 3 5% 5% 5% 7% 34%	1800
	11th to 20th	Day	20% 9% 3 7% 6% 4 5% 4 4 7% 29%	1800
	21st to end	Day	25% 10% 4 7% 6% 4 4 5% 4 6% 26%	1953
November	1st to 10th	Day	15% 9% 4 6% 6% 4 5% 5% 6% 7% 35%	1605
	11th to 20th	Day	16% 10% 5% 8% 6% 3 5% 4 6% 8% 30%	1520
	21st to end	Day	21% 12% 4 7% 5% 4 6% 5% 4 7% 25%	1520
December	1st to 10th	Day	17% 16% 5% 9% 7% 5% 5% 4 4 6% 22%	1520
	11th to 20th	Day	17% 15% 5% 8% 6% 3 5% 4 4 4 29%	1906
	21st to end	Day	28% 14% 5% 8% 6% 3 4 4 3 5% 20%	2772
January	1st to 10th	Night	18% 12% 6% 8% 7% 4 6% 5% 4 5% 25%	2649
	11th to 20th	Night	19% 13% 6% 10% 6% 3 6% 4 5% 5% 23%	2598
	21st to end	Night	13% 14% 5% 10% 7% 3 5% 4 5% 6% 29%	2574
February	1st to 10th	Night	13% 15% 5% 9% 7% 4 5% 5% 5% 6% 25%	2340
	11th to 20th	Night	14% 12% 6% 7% 6% 4 5% 5% 5% 6% 30%	2273
	21st to end	Night	15% 11% 5% 8% 5% 3 5% 5% 5% 7% 32%	1842
March	1st to 10th	Night	14% 9% 4 8% 7% 4 4 4 5% 6% 35%	2033
	11th to 20th	Night	16% 12% 5% 6% 5% 3 4 5% 4 5% 35%	1979
	21st to end	Night	16% 7% 4 6% 6% 3 4 5% 5% 5% 41%	2142
April	1st to 10th	Night	20% 9% 3 6% 5% 3 4 4 5% 6% 36%	1800
	11th to 20th	Night	18% 7% 3 6% 5% 3 4 5% 5% 6% 38%	1775
	21st to end	Night	18% 6% 3 6% 5% 3 5% 6% 7% 7% 34%	1652
May	1st to 10th	Night	19% 5% 3 5% 5% 3 6% 4 6% 7% 37%	1522
	11th to 20th	Night	12% 5% 2 5% 4 3 5% 5% 6% 8% 44%	1415
	21st to end	Night	10% 5% 2 5% 4 3 5% 4 5% 9% 48%	1550
June	1st to 10th	Night	15% 4 2 5% 6% 3 5% 5% 6% 9% 39%	1440
	11th to 20th	Night	10% 5% 2 5% 5% 4 5% 5% 7% 7% 46%	1440
	21st to end	Night	13% 6% 2 5% 5% 3 5% 5% 5% 7% 43%	1440
July	1st to 10th	Night	6% 4 3 4 5% 3 5% 3 6% 7% 53%	1440
	11th to 20th	Night	10% 5% 2 4 5% 3 5% 5% 6% 8% 47%	1440
	21st to end	Night	9% 4 2 4 5% 3 5% 5% 6% 7% 50%	1598
August	1st to 10th	Night	8% 5% 2 5% 5% 3 3 4 6% 9% 48%	1611
	11th to 20th	Night	8% 5% 2 5% 5% 3 4 5% 5% 9% 48%	1598
	21st to end	Night	9% 6% 3 5% 4 3 5% 5% 6% 8% 47%	1921
September	1st to 10th	Night	11% 5% 2 5% 5% 3 4 5% 6% 8% 46%	1800
	11th to 20th	Night	12% 4 2 4 4 3 4 4 6% 7% 52%	1800
	21st to end	Night	15% 6% 3 5% 5% 3 4 5% 4 6% 45%	2078
October	1st to 10th	Night	17% 7% 3 5% 5% 3 4 5% 5% 7% 38%	2160
	11th to 20th	Night	20% 8% 3 7% 6% 3 5% 4 4 7% 33%	2160
	21st to end	Night	22% 10% 3 6% 6% 3 5% 5% 5% 6% 29%	2402
November	1st to 10th	Night	18% 8% 2 5% 5% 3 4 5% 5% 6% 39%	2469
	11th to 20th	Night	17% 9% 3 6% 6% 4 5% 5% 5% 8% 31%	2660
	21st to end	Night	20% 10% 4 7% 5% 3 5% 5% 6% 6% 27%	2660
December	1st to 10th	Night	19% 13% 5% 7% 6% 4 4 5% 6% 8% 22%	2660
	11th to 20th	Night	18% 14% 4 8% 6% 3 4 4 5% 5% 28%	3288
	21st to end	Night	29% 15% 4 9% 6% 3 4 4 4 5% 16%	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	56% 8% 14% 15% 7%	1518
	11th to 20th	Day	63% 7% 9% 11% 10% 1	1502
	21st to end	Day	60% 7% 10% 12% 9% 2	1782
February	1st to 10th	Day	62% 8% 10% 14% 5% 1	1620
	11th to 20th	Day	58% 6% 11% 13% 10% 2	1582
	21st to end	Day	61% 5% 10% 14% 9% 1	1413
March	1st to 10th	Day	53% 7% 15% 15% 9% 2	1916
	11th to 20th	Day	53% 5% 12% 17% 11% 2	1980
	21st to end	Day	49% 6% 8% 18% 15% 4	2214
April	1st to 10th	Day	52% 6% 9% 19% 11% 3	2160
	11th to 20th	Day	46% 4 11% 22% 15% 1	2134
	21st to end	Day	51% 6% 10% 18% 13% 2	2322
May	1st to 10th	Day	47% 7% 11% 18% 15% 3	2438
	11th to 20th	Day	42% 7% 12% 23% 15% 1	2482
	21st to end	Day	40% 7% 16% 21% 14% 2	2725
June	1st to 10th	Day	45% 8% 14% 18% 14% 1	2520
	11th to 20th	Day	39% 8% 14% 24% 13% 2	2520
	21st to end	Day	43% 9% 14% 22% 12% 1	2520
July	1st to 10th	Day	33% 9% 14% 26% 16% 1	2450
	11th to 20th	Day	37% 9% 17% 27% 10%	2445
	21st to end	Day	38% 11% 15% 24% 11% 1	2565
August	1st to 10th	Day	35% 10% 18% 24% 11% 1	2314
	11th to 20th	Day	38% 9% 17% 24% 11%	2303
	21st to end	Day	37% 9% 15% 26% 11% 1	2417
September	1st to 10th	Day	37% 8% 15% 27% 12% 1	2160
	11th to 20th	Day	32% 8% 15% 29% 15% 1	2160
	21st to end	Day	41% 8% 16% 27% 8%	1878
October	1st to 10th	Day	48% 7% 14% 19% 11% 1	1800
	11th to 20th	Day	53% 8% 15% 17% 6% 1	1800
	21st to end	Day	59% 7% 11% 14% 8%	1953
November	1st to 10th	Day	46% 8% 16% 19% 10% 1	1605
	11th to 20th	Day	51% 8% 15% 15% 9% 1	1520
	21st to end	Day	59% 8% 13% 13% 7%	1520
December	1st to 10th	Day	63% 8% 12% 12% 6%	1520
	11th to 20th	Day	58% 8% 13% 12% 8%	1906
	21st to end	Day	67% 6% 10% 12% 5%	2772
January	1st to 10th	Night	60% 7% 11% 15% 7%	2649
	11th to 20th	Night	63% 7% 9% 12% 7% 1	2598
	21st to end	Night	57% 7% 9% 16% 10% 1	2574
February	1st to 10th	Night	59% 7% 12% 16% 5% 1	2340
	11th to 20th	Night	54% 7% 11% 19% 9% 1	2275
	21st to end	Night	51% 7% 14% 19% 9% 1	1842
March	1st to 10th	Night	50% 7% 13% 18% 11% 2	2043
	11th to 20th	Night	50% 6% 11% 20% 12% 1	1980
	21st to end	Night	45% 5% 9% 21% 16% 4	2142
April	1st to 10th	Night	49% 5% 10% 21% 14% 2	1800
	11th to 20th	Night	45% 6% 11% 18% 17% 2	1775
	21st to end	Night	45% 9% 13% 16% 15% 2	1652
May	1st to 10th	Night	45% 7% 10% 18% 16% 3	1522
	11th to 20th	Night	37% 7% 12% 24% 16% 4	1416
	21st to end	Night	33% 8% 14% 22% 19% 4	1551
June	1st to 10th	Night	41% 7% 13% 22% 15% 2	1440
	11th to 20th	Night	35% 8% 13% 20% 20% 3	1440
	21st to end	Night	40% 7% 15% 22% 14% 2	1440
July	1st to 10th	Night	29% 7% 13% 26% 23% 2	1400
	11th to 20th	Night	33% 7% 14% 29% 17%	1392
	21st to end	Night	31% 7% 16% 32% 12% 1	1509
August	1st to 10th	Night	33% 8% 17% 28% 13% 1	1600
	11th to 20th	Night	33% 8% 19% 26% 14% 1	1598
	21st to end	Night	33% 9% 13% 29% 14% 1	1921
September	1st to 10th	Night	35% 9% 16% 25% 14% 1	1800
	11th to 20th	Night	31% 7% 14% 31% 17% 1	1800
	21st to end	Night	40% 8% 11% 28% 12% 1	2078
October	1st to 10th	Night	44% 8% 13% 20% 13% 1	2160
	11th to 20th	Night	52% 7% 14% 20% 8%	2160
	21st to end	Night	56% 7% 12% 14% 10%	2402
November	1st to 10th	Night	45% 7% 14% 23% 11% 1	2469
	11th to 20th	Night	49% 9% 14% 17% 9% 2	2660
	21st to end	Night	53% 10% 16% 16% 5%	2660
December	1st to 10th	Night	59% 9% 14% 14% 4	2660
	11th to 20th	Night	58% 8% 12% 16% 6% 1	3288
	21st to end	Night	69% 7% 10% 10% 4	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	23% 24% 32% 16% 4 1	180
	11th to 20th	Day	26% 26% 29% 16% 3 1	178
	21st to end	Day	26% 23% 31% 14% 5% 1	264
February	1st to 10th	Day	33% 27% 29% 10% 1	240
	11th to 20th	Day	28% 28% 38% 7%	240
	21st to end	Day	35% 23% 34% 8%	279
March	1st to 10th	Day	22% 23% 36% 15% 4	420
	11th to 20th	Day	27% 20% 34% 15% 3	420
	21st to end	Day	32% 17% 31% 13% 6% 1	462
April	1st to 10th	Day	26% 22% 34% 11% 6%	420
	11th to 20th	Day	29% 20% 24% 16% 8% 3	412
	21st to end	Day	27% 22% 31% 13% 5% 2	420
May	1st to 10th	Day	23% 18% 30% 19% 5% 4	423
	11th to 20th	Day	20% 15% 34% 20% 8% 3	447
	21st to end	Day	15% 13% 35% 20% 12% 4	485
June	1st to 10th	Day	18% 14% 36% 23% 7% 2	450
	11th to 20th	Day	14% 14% 31% 24% 12% 3	450
	21st to end	Day	19% 11% 32% 25% 10% 3	450
July	1st to 10th	Day	9% 9% 31% 30% 17% 4	445
	11th to 20th	Day	15% 8% 29% 26% 17% 5%	444
	21st to end	Day	9% 10% 36% 29% 11% 4	488
August	1st to 10th	Day	8% 8% 31% 30% 15% 7%	446
	11th to 20th	Day	12% 6% 28% 29% 18% 7%	439
	21st to end	Day	13% 11% 31% 25% 13% 8%	495
September	1st to 10th	Day	11% 10% 33% 26% 12% 8%	450
	11th to 20th	Day	12% 10% 26% 26% 17% 10%	450
	21st to end	Day	15% 15% 28% 24% 13% 6%	450
October	1st to 10th	Day	22% 19% 23% 17% 14% 6%	450
	11th to 20th	Day	24% 21% 31% 16% 7% 1	450
	21st to end	Day	31% 19% 27% 19% 4	481
November	1st to 10th	Day	24% 20% 26% 19% 10% 1	299
	11th to 20th	Day	24% 24% 33% 14% 4 1	180
	21st to end	Day	24% 24% 33% 13% 5%	180
December	1st to 10th	Day	28% 19% 33% 14% 5%	180
	11th to 20th	Day	32% 23% 30% 12% 2 1	180
	21st to end	Day	36% 20% 33% 10% 1	198
January	1st to 10th	Night	25% 21% 31% 18% 4	760
	11th to 20th	Night	25% 18% 33% 18% 5%	748
	21st to end	Night	20% 17% 34% 23% 5% 1	792
February	1st to 10th	Night	22% 20% 39% 17% 2	720
	11th to 20th	Night	22% 19% 37% 17% 4	703
	21st to end	Night	23% 21% 36% 17% 3	592
March	1st to 10th	Night	19% 19% 37% 22% 3	720
	11th to 20th	Night	24% 16% 34% 20% 4 1	720
	21st to end	Night	20% 14% 35% 23% 7% 1	792
April	1st to 10th	Night	22% 16% 35% 23% 4	720
	11th to 20th	Night	21% 16% 32% 21% 8% 1	711
	21st to end	Night	21% 11% 31% 26% 10% 1	572
May	1st to 10th	Night	21% 8% 30% 27% 12% 2	442
	11th to 20th	Night	14% 8% 37% 31% 10%	354
	21st to end	Night	12% 6% 34% 33% 14% 1	389
June	1st to 10th	Night	13% 6% 37% 30% 13% 1	360
	11th to 20th	Night	11% 9% 31% 34% 15% 1	360
	21st to end	Night	14% 8% 28% 36% 14% 1	360
July	1st to 10th	Night	7% 5% 28% 43% 17% 1	350
	11th to 20th	Night	10% 2 28% 36% 23% 1	348
	21st to end	Night	9% 2 30% 41% 17% 1	418
August	1st to 10th	Night	10% 4 22% 36% 27% 2	537
	11th to 20th	Night	8% 7% 21% 37% 25% 3	534
	21st to end	Night	11% 5% 28% 34% 19% 2	733
September	1st to 10th	Night	12% 6% 30% 31% 19% 3	720
	11th to 20th	Night	13% 6% 22% 31% 25% 4	720
	21st to end	Night	17% 9% 24% 27% 19% 3	720
October	1st to 10th	Night	22% 9% 28% 23% 16% 2	720
	11th to 20th	Night	22% 16% 31% 23% 9%	720
	21st to end	Night	27% 14% 33% 22% 5%	792
November	1st to 10th	Night	24% 13% 25% 28% 9% 1	740
	11th to 20th	Night	22% 18% 33% 20% 6% 1	760
	21st to end	Night	27% 16% 32% 20% 6%	760
December	1st to 10th	Night	28% 19% 32% 18% 3	760
	11th to 20th	Night	25% 18% 34% 18% 3	760
	21st to end	Night	32% 16% 34% 15% 3	836

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