Peace River
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Peace River clear sky chart from 2005-11-06 to 2025-10-04.

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	9% 8% 3 9% 6% 6% 5% 5% 7% 8% 34%	131080
	Night	7% 10% 4 10% 6% 6% 6% 5% 7% 8% 31%	126983
Transparency	Day	45% 6% 17% 24% 8% 1	130751
	Night	49% 6% 16% 21% 8% 1	126889
Seeing	Day	13% 6% 22% 30% 21% 8%	17940
	Night	13% 5% 21% 38% 20% 3	25816

By Month

Percentage Cloud Cover NW (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	6% 13% 6% 12% 11% 9% 7% 5% 8% 6% 16%	2719
	11th to 20th	Day	6% 12% 3 10% 7% 7% 5% 5% 8% 9% 30%	2702
	21st to end	Day	5% 11% 6% 12% 7% 5% 5% 4 6% 7% 31%	3559
February	1st to 10th	Day	7% 13% 4 11% 7% 6% 9% 7% 8% 10% 19%	1600
	11th to 20th	Day	5% 10% 5% 12% 7% 6% 7% 6% 8% 8% 26%	1560
	21st to end	Day	4 10% 5% 13% 8% 8% 7% 6% 8% 9% 22%	1579
March	1st to 10th	Day	3 9% 5% 12% 7% 7% 7% 5% 7% 8% 29%	4518
	11th to 20th	Day	4 11% 5% 14% 6% 6% 6% 5% 6% 9% 29%	4682
	21st to end	Day	4 10% 4 11% 6% 6% 6% 4 6% 8% 35%	5938
April	1st to 10th	Day	5% 10% 3 7% 7% 6% 5% 5% 7% 8% 36%	2413
	11th to 20th	Day	8% 10% 4 7% 6% 6% 5% 5% 7% 8% 34%	2584
	21st to end	Day	11% 11% 3 8% 7% 5% 5% 4 5% 8% 32%	2800
May	1st to 10th	Day	9% 7% 2 7% 5% 5% 5% 5% 7% 9% 39%	6588
	11th to 20th	Day	9% 8% 3 9% 6% 6% 6% 5% 7% 9% 30%	6751
	21st to end	Day	11% 7% 3 7% 5% 6% 6% 5% 7% 9% 35%	7907
June	1st to 10th	Day	14% 7% 2 8% 6% 5% 5% 4 6% 7% 35%	3200
	11th to 20th	Day	21% 9% 3 8% 6% 6% 5% 4 6% 6% 26%	3200
	21st to end	Day	10% 7% 2 7% 6% 5% 6% 5% 6% 8% 39%	3200
July	1st to 10th	Day	9% 6% 2 6% 5% 5% 5% 5% 7% 9% 40%	7240
	11th to 20th	Day	6% 4 2 6% 5% 6% 6% 5% 7% 9% 44%	7240
	21st to end	Day	12% 5% 2 5% 4 5% 4 4 6% 8% 45%	7751
August	1st to 10th	Day	10% 5% 2 6% 5% 5% 5% 4 6% 8% 43%	4591
	11th to 20th	Day	11% 6% 3 7% 5% 5% 6% 4 6% 8% 39%	4470
	21st to end	Day	12% 5% 2 8% 5% 4 5% 4 6% 8% 40%	4797
September	1st to 10th	Day	14% 6% 2 6% 5% 4 4 4 5% 8% 42%	2433
	11th to 20th	Day	10% 7% 3 6% 5% 4 6% 4 7% 9% 40%	2325
	21st to end	Day	10% 8% 3 7% 5% 4 5% 4 7% 9% 39%	2200
October	1st to 10th	Day	12% 10% 4 7% 5% 5% 5% 5% 6% 8% 33%	3226
	11th to 20th	Day	12% 9% 4 9% 5% 4 5% 4 6% 8% 34%	2842
	21st to end	Day	9% 13% 5% 10% 5% 4 4 4 6% 8% 31%	3080
November	1st to 10th	Day	10% 12% 5% 11% 7% 5% 7% 5% 6% 7% 25%	1401
	11th to 20th	Day	7% 13% 6% 13% 7% 6% 7% 5% 6% 8% 22%	1400
	21st to end	Day	7% 15% 5% 13% 6% 7% 5% 4 6% 7% 25%	1370
December	1st to 10th	Day	11% 15% 6% 16% 9% 6% 7% 5% 4 5% 15%	1960
	11th to 20th	Day	9% 14% 4 11% 9% 8% 7% 6% 7% 8% 17%	2262
	21st to end	Day	3 8% 4 14% 10% 6% 5% 4 6% 7% 33%	2992
January	1st to 10th	Night	5% 14% 7% 16% 9% 7% 6% 4 6% 7% 20%	7226
	11th to 20th	Night	5% 11% 4 10% 6% 5% 7% 5% 8% 8% 31%	7196
	21st to end	Night	7% 15% 5% 12% 7% 6% 5% 4 5% 7% 26%	7442
February	1st to 10th	Night	6% 12% 6% 11% 7% 6% 6% 5% 6% 9% 26%	2800
	11th to 20th	Night	5% 13% 5% 12% 8% 7% 5% 5% 5% 7% 28%	2726
	21st to end	Night	3 10% 4 12% 7% 6% 6% 5% 8% 9% 31%	2048
March	1st to 10th	Night	3 7% 4 10% 6% 8% 7% 6% 8% 9% 32%	5376
	11th to 20th	Night	4 10% 4 11% 7% 6% 7% 5% 8% 10% 28%	5317
	21st to end	Night	5% 11% 4 10% 5% 5% 5% 3 5% 8% 38%	5033
April	1st to 10th	Night	5% 11% 3 8% 5% 6% 5% 5% 6% 7% 38%	1986
	11th to 20th	Night	9% 11% 3 9% 6% 5% 5% 5% 7% 8% 32%	1762
	21st to end	Night	11% 12% 4 7% 6% 7% 5% 5% 6% 7% 30%	1600
May	1st to 10th	Night	8% 8% 3 9% 6% 5% 5% 3 5% 7% 41%	3371
	11th to 20th	Night	8% 8% 4 10% 7% 7% 6% 5% 7% 8% 30%	3141
	21st to end	Night	10% 6% 3 7% 5% 5% 5% 5% 8% 9% 37%	2968
June	1st to 10th	Night	12% 6% 3 8% 6% 6% 6% 4 8% 7% 35%	1200
	11th to 20th	Night	17% 8% 3 7% 6% 5% 5% 4 8% 8% 28%	1200
	21st to end	Night	10% 6% 2 6% 5% 5% 5% 5% 8% 10% 39%	1200
July	1st to 10th	Night	13% 8% 3 8% 5% 5% 5% 4 6% 8% 36%	2720
	11th to 20th	Night	6% 6% 3 8% 6% 4 5% 5% 7% 8% 42%	2720
	21st to end	Night	10% 5% 2 5% 4 4 4 4 6% 10% 45%	3091
August	1st to 10th	Night	10% 6% 3 6% 4 5% 5% 4 7% 7% 44%	2543
	11th to 20th	Night	10% 7% 2 7% 5% 4 5% 4 6% 7% 45%	2577
	21st to end	Night	13% 6% 2 6% 5% 4 5% 4 8% 8% 40%	3108
September	1st to 10th	Night	13% 6% 3 6% 5% 5% 5% 5% 6% 8% 39%	1965
	11th to 20th	Night	8% 7% 2 7% 5% 4 6% 4 7% 8% 41%	2075
	21st to end	Night	9% 9% 2 8% 5% 6% 4 4 6% 8% 41%	2200
October	1st to 10th	Night	9% 11% 3 9% 5% 5% 5% 4 6% 7% 34%	3815
	11th to 20th	Night	8% 8% 3 7% 5% 5% 4 4 6% 9% 40%	4086
	21st to end	Night	8% 12% 3 9% 6% 6% 6% 4 6% 7% 32%	4475
November	1st to 10th	Night	11% 14% 5% 11% 6% 5% 5% 5% 6% 6% 27%	2875
	11th to 20th	Night	9% 14% 5% 11% 7% 7% 7% 5% 6% 6% 23%	3000
	21st to end	Night	6% 15% 5% 13% 8% 5% 5% 4 6% 8% 24%	3027
December	1st to 10th	Night	11% 14% 5% 14% 8% 6% 6% 5% 6% 7% 20%	5220
	11th to 20th	Night	8% 16% 5% 13% 8% 6% 6% 5% 7% 7% 19%	5930
	21st to end	Night	3 9% 4 13% 9% 6% 6% 4 6% 8% 30%	7964

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	64% 6% 12% 11% 8%	2719
	11th to 20th	Day	48% 4 14% 16% 16% 1	2720
	21st to end	Day	51% 6% 20% 17% 5%	3559
February	1st to 10th	Day	55% 6% 14% 16% 9%	1600
	11th to 20th	Day	51% 7% 16% 19% 6%	1568
	21st to end	Day	54% 6% 16% 16% 7%	1579
March	1st to 10th	Day	50% 5% 16% 23% 6%	4518
	11th to 20th	Day	50% 8% 18% 20% 5%	4682
	21st to end	Day	45% 5% 12% 25% 13% 1	5938
April	1st to 10th	Day	43% 6% 16% 25% 10%	2413
	11th to 20th	Day	46% 5% 14% 24% 10% 1	2584
	21st to end	Day	50% 6% 12% 24% 8%	2800
May	1st to 10th	Day	39% 5% 11% 28% 15% 3	6588
	11th to 20th	Day	48% 6% 13% 25% 8% 1	6755
	21st to end	Day	43% 6% 17% 23% 11% 1	7908
June	1st to 10th	Day	46% 6% 14% 25% 9% 1	3200
	11th to 20th	Day	57% 7% 13% 18% 5%	3200
	21st to end	Day	41% 6% 19% 26% 8%	3200
July	1st to 10th	Day	38% 6% 22% 26% 8% 1	7161
	11th to 20th	Day	35% 6% 17% 33% 9% 1	7153
	21st to end	Day	37% 5% 21% 29% 8%	7532
August	1st to 10th	Day	37% 7% 21% 33% 3	4573
	11th to 20th	Day	41% 6% 18% 25% 10%	4512
	21st to end	Day	41% 6% 25% 23% 4	4796
September	1st to 10th	Day	39% 6% 25% 25% 4	2433
	11th to 20th	Day	39% 6% 24% 26% 5%	2325
	21st to end	Day	40% 7% 20% 24% 9%	2200
October	1st to 10th	Day	47% 7% 20% 22% 4	3226
	11th to 20th	Day	47% 4 19% 26% 4	2842
	21st to end	Day	51% 6% 22% 19% 3	3080
November	1st to 10th	Day	56% 7% 14% 20% 3	1401
	11th to 20th	Day	57% 9% 17% 15% 3	1400
	21st to end	Day	56% 7% 16% 16% 4 1	1370
December	1st to 10th	Day	70% 6% 9% 9% 5%	1960
	11th to 20th	Day	61% 8% 14% 14% 3	2264
	21st to end	Day	50% 5% 14% 23% 6% 1	2992
January	1st to 10th	Night	63% 6% 11% 13% 7%	7226
	11th to 20th	Night	48% 6% 13% 16% 16% 1	7240
	21st to end	Night	56% 7% 18% 14% 5%	7442
February	1st to 10th	Night	53% 5% 14% 19% 9% 1	2800
	11th to 20th	Night	54% 6% 15% 18% 7% 1	2728
	21st to end	Night	47% 6% 17% 22% 8%	2048
March	1st to 10th	Night	43% 7% 16% 24% 9%	5376
	11th to 20th	Night	47% 6% 18% 23% 6%	5318
	21st to end	Night	42% 6% 9% 28% 15% 1	5033
April	1st to 10th	Night	43% 5% 10% 26% 14% 2	1986
	11th to 20th	Night	47% 5% 10% 24% 13% 1	1762
	21st to end	Night	51% 5% 11% 23% 9% 1	1600
May	1st to 10th	Night	42% 4 12% 23% 18% 2	3368
	11th to 20th	Night	46% 7% 11% 24% 11% 1	3141
	21st to end	Night	39% 6% 19% 27% 7% 2	2968
June	1st to 10th	Night	46% 5% 12% 26% 11% 1	1200
	11th to 20th	Night	51% 5% 16% 22% 5%	1200
	21st to end	Night	37% 7% 19% 26% 11%	1200
July	1st to 10th	Night	45% 5% 16% 24% 9%	2690
	11th to 20th	Night	37% 5% 14% 33% 9% 1	2684
	21st to end	Night	34% 6% 20% 31% 9%	3005
August	1st to 10th	Night	36% 7% 18% 35% 4	2536
	11th to 20th	Night	37% 7% 19% 24% 13%	2601
	21st to end	Night	39% 5% 26% 23% 5%	3108
September	1st to 10th	Night	41% 7% 20% 25% 7% 1	1965
	11th to 20th	Night	39% 5% 21% 28% 7%	2075
	21st to end	Night	42% 6% 16% 25% 10% 1	2200
October	1st to 10th	Night	47% 6% 18% 20% 9%	3815
	11th to 20th	Night	40% 5% 19% 30% 6%	4086
	21st to end	Night	50% 6% 19% 21% 4	4475
November	1st to 10th	Night	56% 6% 14% 20% 3	2875
	11th to 20th	Night	59% 8% 14% 16% 4	3000
	21st to end	Night	57% 7% 16% 15% 4 1	3027
December	1st to 10th	Night	62% 7% 11% 14% 5%	5220
	11th to 20th	Night	61% 6% 15% 14% 4	5927
	21st to end	Night	51% 5% 17% 22% 5%	7964

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	12% 5% 23% 35% 21% 6%	200
	11th to 20th	Day	17% 6% 21% 32% 22% 4	200
	21st to end	Day	13% 5% 25% 32% 23% 3	220
February	1st to 10th	Day	11% 4 29% 30% 18% 9%	200
	11th to 20th	Day	9% 4 27% 34% 20% 8%	200
	21st to end	Day	8% 4 29% 34% 18% 7%	369
March	1st to 10th	Day	7% 5% 26% 33% 22% 7%	500
	11th to 20th	Day	9% 5% 26% 31% 23% 6%	500
	21st to end	Day	14% 5% 24% 30% 20% 7%	550
April	1st to 10th	Day	9% 6% 25% 33% 20% 7%	500
	11th to 20th	Day	12% 10% 25% 25% 20% 8%	492
	21st to end	Day	14% 10% 24% 28% 16% 7%	500
May	1st to 10th	Day	13% 8% 29% 25% 21% 5%	615
	11th to 20th	Day	12% 6% 18% 34% 22% 8%	729
	21st to end	Day	14% 6% 18% 29% 26% 7%	1006
June	1st to 10th	Day	16% 8% 23% 28% 21% 4	930
	11th to 20th	Day	23% 6% 15% 26% 21% 8%	930
	21st to end	Day	11% 6% 15% 28% 27% 12%	930
July	1st to 10th	Day	13% 5% 17% 29% 28% 9%	916
	11th to 20th	Day	11% 5% 15% 29% 29% 11%	912
	21st to end	Day	13% 4 17% 31% 23% 12%	962
August	1st to 10th	Day	14% 7% 15% 24% 24% 16%	564
	11th to 20th	Day	9% 9% 25% 32% 20% 4	517
	21st to end	Day	15% 6% 25% 27% 19% 9%	583
September	1st to 10th	Day	16% 5% 23% 29% 20% 7%	530
	11th to 20th	Day	13% 7% 21% 31% 20% 9%	530
	21st to end	Day	14% 12% 30% 25% 16% 3	530
October	1st to 10th	Day	17% 10% 23% 30% 17% 4	480
	11th to 20th	Day	19% 5% 24% 29% 18% 4	300
	21st to end	Day	18% 4 25% 35% 13% 5%	325
November	1st to 10th	Day	13% 4 34% 29% 17% 5%	200
	11th to 20th	Day	16% 5% 32% 26% 18% 4	200
	21st to end	Day	11% 7% 31% 32% 17% 3	200
December	1st to 10th	Day	8% 9% 28% 34% 17% 6%	200
	11th to 20th	Day	12% 7% 25% 34% 20% 3	200
	21st to end	Day	9% 2 20% 39% 23% 7%	220
January	1st to 10th	Night	13% 4 24% 39% 18% 3	1100
	11th to 20th	Night	13% 6% 25% 37% 17% 2	1100
	21st to end	Night	17% 7% 27% 33% 14% 1	1037
February	1st to 10th	Night	12% 4 22% 36% 22% 4	800
	11th to 20th	Night	12% 3 20% 45% 18% 2	784
	21st to end	Night	6% 3 26% 40% 21% 4	660
March	1st to 10th	Night	9% 5% 24% 36% 23% 4	800
	11th to 20th	Night	13% 4 22% 42% 19% 2	800
	21st to end	Night	13% 4 19% 38% 24% 3	880
April	1st to 10th	Night	10% 4 19% 41% 23% 3	786
	11th to 20th	Night	13% 4 22% 34% 23% 3	574
	21st to end	Night	15% 3 22% 38% 20% 2	400
May	1st to 10th	Night	14% 5% 16% 38% 25% 2	400
	11th to 20th	Night	9% 5% 22% 36% 25% 3	394
	21st to end	Night	16% 3 12% 40% 25% 3	433
June	1st to 10th	Night	14% 4 13% 42% 27%	400
	11th to 20th	Night	20% 3 12% 34% 27% 4	400
	21st to end	Night	12% 3 14% 39% 30% 4	400
July	1st to 10th	Night	14% 4 13% 35% 31% 3	390
	11th to 20th	Night	11% 3 10% 38% 34% 4	388
	21st to end	Night	13% 2 12% 35% 35% 3	438
August	1st to 10th	Night	10% 3 9% 32% 39% 7%	398
	11th to 20th	Night	8% 3 17% 46% 24% 2	396
	21st to end	Night	15% 2 14% 42% 24% 3	575
September	1st to 10th	Night	16% 2 13% 38% 26% 4	765
	11th to 20th	Night	10% 3 16% 41% 27% 3	800
	21st to end	Night	13% 6% 28% 34% 15% 3	800
October	1st to 10th	Night	15% 6% 22% 38% 17% 2	772
	11th to 20th	Night	14% 5% 22% 39% 17% 2	760
	21st to end	Night	19% 7% 20% 38% 14% 2	836
November	1st to 10th	Night	17% 7% 23% 35% 16% 2	925
	11th to 20th	Night	15% 8% 25% 39% 12% 1	1000
	21st to end	Night	13% 6% 28% 39% 12% 2	1015
December	1st to 10th	Night	15% 5% 27% 36% 14% 3	1100
	11th to 20th	Night	14% 5% 25% 39% 15% 2	1100
	21st to end	Night	11% 4 23% 37% 22% 3	1210

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