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 2024-01-12.

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	11% 8% 4 7% 7% 4 6% 6% 6% 8% 33%	74553
	Night	9% 10% 4 8% 7% 4 6% 6% 6% 8% 32%	75149
Transparency	Day	47% 7% 18% 22% 6%	74212
	Night	49% 6% 16% 21% 7% 1	75008
Seeing	Day	14% 6% 21% 30% 22% 8%	15432
	Night	14% 5% 21% 38% 21% 3	23667

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% 12% 6% 12% 12% 4 8% 6% 6% 7% 21%	1139
	11th to 20th	Day	12% 15% 4 7% 9% 6% 6% 5% 7% 5% 24%	1086
	21st to end	Day	8% 13% 5% 11% 9% 5% 6% 6% 6% 7% 24%	1405
February	1st to 10th	Day	8% 12% 5% 10% 8% 4 8% 10% 8% 9% 19%	1440
	11th to 20th	Day	6% 11% 5% 12% 9% 6% 7% 8% 7% 8% 23%	1400
	21st to end	Day	5% 9% 6% 11% 9% 6% 8% 7% 7% 10% 22%	1416
March	1st to 10th	Day	5% 11% 5% 8% 8% 5% 7% 6% 7% 8% 29%	1800
	11th to 20th	Day	7% 12% 5% 10% 7% 4 5% 5% 5% 8% 31%	1844
	21st to end	Day	7% 14% 5% 9% 7% 3 6% 6% 6% 9% 28%	2358
April	1st to 10th	Day	6% 9% 4 6% 8% 5% 6% 6% 6% 8% 36%	2171
	11th to 20th	Day	8% 10% 5% 7% 7% 4 5% 6% 7% 8% 33%	2322
	21st to end	Day	12% 10% 4 8% 7% 4 5% 5% 5% 8% 32%	2520
May	1st to 10th	Day	11% 8% 4 7% 5% 4 5% 5% 7% 8% 37%	2620
	11th to 20th	Day	10% 6% 3 5% 5% 3 5% 6% 6% 8% 42%	2657
	21st to end	Day	14% 6% 3 6% 6% 4 5% 5% 6% 9% 36%	3111
June	1st to 10th	Day	14% 7% 2 6% 6% 4 5% 5% 6% 8% 37%	2880
	11th to 20th	Day	21% 8% 4 7% 6% 4 5% 5% 6% 6% 27%	2880
	21st to end	Day	11% 6% 3 6% 7% 4 6% 6% 6% 8% 38%	2880
July	1st to 10th	Day	13% 6% 3 5% 5% 4 5% 6% 7% 10% 37%	2880
	11th to 20th	Day	12% 6% 2 6% 5% 4 6% 7% 7% 9% 36%	2880
	21st to end	Day	11% 5% 3 5% 5% 4 5% 5% 7% 8% 43%	3090
August	1st to 10th	Day	11% 5% 2 4 6% 5% 6% 7% 7% 8% 37%	2541
	11th to 20th	Day	9% 5% 3 6% 6% 3 6% 6% 6% 9% 42%	2475
	21st to end	Day	13% 6% 2 6% 6% 4 5% 6% 7% 8% 36%	2651
September	1st to 10th	Day	15% 6% 2 5% 6% 3 4 5% 5% 9% 40%	2191
	11th to 20th	Day	10% 7% 3 5% 6% 3 6% 5% 7% 8% 40%	2093
	21st to end	Day	9% 7% 3 6% 5% 3 5% 5% 7% 10% 40%	1980
October	1st to 10th	Day	12% 10% 4 6% 6% 4 6% 6% 6% 7% 34%	1815
	11th to 20th	Day	13% 10% 4 9% 7% 3 5% 5% 7% 7% 30%	1620
	21st to end	Day	12% 12% 5% 9% 8% 4 5% 5% 6% 6% 28%	1774
November	1st to 10th	Day	10% 11% 6% 10% 8% 4 7% 6% 6% 7% 25%	1330
	11th to 20th	Day	8% 11% 6% 12% 8% 4 8% 7% 6% 8% 23%	1330
	21st to end	Day	7% 14% 6% 10% 7% 6% 6% 5% 5% 7% 27%	1302
December	1st to 10th	Day	8% 13% 6% 10% 9% 4 6% 7% 6% 7% 24%	1140
	11th to 20th	Day	11% 11% 4 9% 11% 5% 7% 6% 6% 9% 21%	1442
	21st to end	Day	4 8% 4 8% 7% 5% 6% 6% 7% 9% 39%	2090
January	1st to 10th	Night	7% 13% 6% 11% 10% 5% 7% 6% 7% 7% 21%	3026
	11th to 20th	Night	9% 13% 6% 11% 7% 5% 6% 5% 7% 7% 23%	2897
	21st to end	Night	10% 15% 5% 11% 10% 4 6% 5% 5% 7% 22%	2968
February	1st to 10th	Night	7% 11% 7% 10% 8% 4 7% 6% 6% 8% 27%	2520
	11th to 20th	Night	6% 13% 6% 12% 9% 5% 6% 6% 5% 7% 26%	2446
	21st to end	Night	3 9% 5% 10% 8% 4 7% 7% 7% 10% 31%	1838
March	1st to 10th	Night	6% 9% 4 8% 7% 4 6% 6% 7% 9% 35%	2160
	11th to 20th	Night	8% 12% 5% 8% 6% 4 5% 6% 7% 9% 30%	2115
	21st to end	Night	7% 14% 4 8% 5% 4 6% 6% 6% 8% 33%	1994
April	1st to 10th	Night	6% 10% 4 7% 6% 4 5% 6% 7% 8% 36%	1788
	11th to 20th	Night	9% 10% 3 7% 7% 4 5% 6% 7% 8% 32%	1584
	21st to end	Night	12% 11% 4 7% 6% 6% 6% 6% 5% 7% 30%	1440
May	1st to 10th	Night	11% 8% 3 7% 7% 4 7% 4 6% 8% 36%	1339
	11th to 20th	Night	8% 6% 3 6% 6% 4 6% 5% 5% 8% 43%	1235
	21st to end	Night	15% 5% 4 7% 6% 2 5% 5% 7% 8% 36%	1164
June	1st to 10th	Night	13% 5% 3 6% 6% 5% 6% 6% 6% 8% 36%	1080
	11th to 20th	Night	17% 8% 4 7% 7% 3 5% 6% 7% 8% 29%	1080
	21st to end	Night	10% 5% 2 5% 6% 4 6% 6% 7% 10% 39%	1080
July	1st to 10th	Night	13% 5% 2 5% 5% 3 6% 5% 7% 8% 42%	1080
	11th to 20th	Night	9% 6% 3 6% 6% 4 5% 8% 8% 10% 35%	1080
	21st to end	Night	12% 4 2 4 5% 3 4 6% 8% 10% 41%	1226
August	1st to 10th	Night	8% 5% 3 6% 4 4 6% 6% 9% 8% 41%	1396
	11th to 20th	Night	6% 4 2 5% 6% 3 6% 5% 8% 9% 46%	1424
	21st to end	Night	14% 6% 2 5% 5% 3 4 5% 8% 8% 40%	1705
September	1st to 10th	Night	14% 6% 3 6% 6% 4 4 6% 6% 8% 38%	1768
	11th to 20th	Night	9% 7% 2 6% 6% 3 6% 6% 6% 8% 41%	1867
	21st to end	Night	9% 8% 2 6% 6% 4 5% 5% 6% 8% 42%	1980
October	1st to 10th	Night	10% 10% 3 9% 6% 3 5% 5% 6% 6% 35%	2141
	11th to 20th	Night	9% 9% 4 7% 6% 4 5% 5% 5% 9% 36%	2340
	21st to end	Night	12% 13% 4 8% 8% 4 5% 5% 5% 6% 31%	2580
November	1st to 10th	Night	12% 13% 5% 10% 7% 4 5% 6% 5% 6% 27%	2727
	11th to 20th	Night	9% 14% 5% 10% 8% 5% 7% 7% 6% 6% 23%	2850
	21st to end	Night	7% 13% 7% 11% 9% 4 6% 5% 6% 8% 25%	2875
December	1st to 10th	Night	8% 11% 5% 11% 10% 6% 6% 6% 6% 7% 24%	3040
	11th to 20th	Night	9% 15% 5% 10% 9% 4 5% 6% 7% 7% 24%	3750
	21st to end	Night	3 8% 4 8% 8% 4 6% 6% 6% 9% 37%	5566

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	60% 7% 14% 13% 6%	1139
	11th to 20th	Day	59% 4 15% 15% 5% 2	1086
	21st to end	Day	59% 7% 15% 15% 4	1405
February	1st to 10th	Day	55% 7% 16% 15% 8%	1440
	11th to 20th	Day	55% 7% 17% 16% 4	1408
	21st to end	Day	55% 6% 15% 17% 8%	1416
March	1st to 10th	Day	48% 7% 20% 19% 7%	1800
	11th to 20th	Day	50% 7% 17% 22% 5%	1844
	21st to end	Day	52% 7% 17% 19% 5%	2358
April	1st to 10th	Day	44% 6% 17% 25% 8%	2171
	11th to 20th	Day	47% 5% 15% 24% 8% 1	2322
	21st to end	Day	51% 6% 12% 23% 7%	2520
May	1st to 10th	Day	44% 6% 15% 23% 11% 1	2620
	11th to 20th	Day	39% 4 13% 27% 14% 2	2661
	21st to end	Day	44% 5% 13% 25% 12% 1	3112
June	1st to 10th	Day	45% 5% 15% 26% 9% 1	2880
	11th to 20th	Day	57% 7% 13% 18% 5%	2880
	21st to end	Day	42% 6% 19% 26% 7%	2880
July	1st to 10th	Day	40% 7% 20% 26% 7% 1	2801
	11th to 20th	Day	42% 9% 27% 20% 2	2793
	21st to end	Day	37% 7% 26% 25% 4	2918
August	1st to 10th	Day	40% 9% 28% 19% 3	2523
	11th to 20th	Day	37% 8% 24% 26% 5%	2475
	21st to end	Day	42% 8% 22% 23% 4	2651
September	1st to 10th	Day	41% 6% 25% 23% 4	2191
	11th to 20th	Day	40% 6% 25% 25% 5%	2093
	21st to end	Day	38% 8% 21% 25% 9%	1980
October	1st to 10th	Day	48% 6% 18% 22% 6%	1815
	11th to 20th	Day	52% 5% 19% 20% 5%	1620
	21st to end	Day	55% 8% 16% 17% 5%	1774
November	1st to 10th	Day	56% 7% 14% 20% 3	1330
	11th to 20th	Day	56% 8% 18% 15% 3	1330
	21st to end	Day	54% 7% 16% 17% 4 2	1302
December	1st to 10th	Day	57% 7% 12% 15% 9% 1	1140
	11th to 20th	Day	59% 8% 12% 17% 4	1444
	21st to end	Day	41% 6% 15% 26% 9% 2	2090
January	1st to 10th	Night	59% 7% 14% 13% 6% 1	3026
	11th to 20th	Night	57% 8% 16% 14% 4 1	2897
	21st to end	Night	61% 6% 12% 13% 8% 1	2968
February	1st to 10th	Night	54% 5% 14% 19% 8% 1	2520
	11th to 20th	Night	57% 5% 15% 17% 5%	2448
	21st to end	Night	46% 6% 18% 21% 9%	1838
March	1st to 10th	Night	43% 6% 18% 24% 9% 1	2160
	11th to 20th	Night	48% 6% 12% 26% 8%	2116
	21st to end	Night	48% 5% 15% 24% 8%	1994
April	1st to 10th	Night	44% 5% 10% 26% 14% 1	1788
	11th to 20th	Night	47% 5% 11% 24% 11% 2	1584
	21st to end	Night	52% 5% 10% 23% 10%	1440
May	1st to 10th	Night	46% 4 12% 25% 12% 1	1339
	11th to 20th	Night	38% 6% 10% 26% 19% 3	1235
	21st to end	Night	44% 4 13% 25% 11% 2	1164
June	1st to 10th	Night	45% 5% 13% 26% 10% 1	1080
	11th to 20th	Night	51% 5% 15% 22% 6%	1080
	21st to end	Night	37% 7% 18% 27% 10%	1080
July	1st to 10th	Night	39% 6% 19% 28% 8%	1050
	11th to 20th	Night	41% 9% 26% 22% 2	1044
	21st to end	Night	33% 8% 28% 25% 5% 1	1158
August	1st to 10th	Night	35% 10% 25% 25% 5%	1389
	11th to 20th	Night	32% 8% 25% 27% 7% 1	1424
	21st to end	Night	40% 6% 20% 26% 7% 1	1705
September	1st to 10th	Night	42% 7% 19% 24% 7% 1	1768
	11th to 20th	Night	39% 6% 21% 27% 7%	1867
	21st to end	Night	40% 6% 17% 27% 10% 1	1980
October	1st to 10th	Night	48% 5% 16% 22% 9% 1	2141
	11th to 20th	Night	45% 7% 17% 25% 6%	2340
	21st to end	Night	53% 6% 15% 20% 6%	2580
November	1st to 10th	Night	56% 6% 14% 20% 3	2727
	11th to 20th	Night	58% 8% 14% 16% 4	2850
	21st to end	Night	56% 7% 17% 15% 4 1	2875
December	1st to 10th	Night	58% 6% 11% 16% 8% 1	3040
	11th to 20th	Night	57% 7% 13% 17% 5%	3747
	21st to end	Night	43% 5% 18% 26% 7% 1	5566

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	11% 4 22% 36% 22% 4	180
	11th to 20th	Day	19% 5% 20% 29% 23% 4	162
	21st to end	Day	15% 1 22% 32% 26% 3	176
February	1st to 10th	Day	13% 4 28% 32% 16% 8%	160
	11th to 20th	Day	11% 4 28% 30% 18% 9%	160
	21st to end	Day	7% 3 26% 35% 20% 8%	308
March	1st to 10th	Day	8% 5% 24% 33% 23% 8%	420
	11th to 20th	Day	10% 4 25% 33% 23% 6%	420
	21st to end	Day	16% 3 25% 30% 19% 7%	462
April	1st to 10th	Day	10% 5% 23% 32% 22% 9%	420
	11th to 20th	Day	13% 9% 25% 23% 22% 8%	412
	21st to end	Day	15% 10% 26% 26% 15% 7%	420
May	1st to 10th	Day	14% 7% 26% 26% 22% 5%	523
	11th to 20th	Day	11% 6% 17% 35% 23% 8%	628
	21st to end	Day	15% 6% 16% 30% 26% 8%	874
June	1st to 10th	Day	15% 7% 23% 28% 22% 5%	810
	11th to 20th	Day	23% 6% 16% 27% 21% 7%	810
	21st to end	Day	12% 6% 16% 27% 25% 13%	810
July	1st to 10th	Day	13% 4 18% 28% 27% 9%	796
	11th to 20th	Day	12% 4 15% 30% 28% 11%	792
	21st to end	Day	13% 3 16% 32% 23% 12%	836
August	1st to 10th	Day	15% 6% 15% 22% 25% 17%	481
	11th to 20th	Day	10% 9% 26% 31% 19% 5%	437
	21st to end	Day	16% 6% 26% 26% 18% 8%	495
September	1st to 10th	Day	18% 4 24% 28% 18% 8%	450
	11th to 20th	Day	14% 8% 21% 29% 20% 8%	450
	21st to end	Day	11% 10% 29% 28% 18% 4	450
October	1st to 10th	Day	16% 10% 22% 30% 18% 4	429
	11th to 20th	Day	19% 5% 23% 30% 19% 4	270
	21st to end	Day	19% 5% 24% 34% 13% 5%	293
November	1st to 10th	Day	13% 3 32% 29% 18% 4	180
	11th to 20th	Day	14% 4 32% 27% 19% 4	180
	21st to end	Day	11% 7% 32% 32% 17% 1	180
December	1st to 10th	Day	6% 6% 29% 34% 18% 6%	180
	11th to 20th	Day	11% 7% 26% 33% 21% 3	180
	21st to end	Day	10% 3 18% 42% 21% 7%	198
January	1st to 10th	Night	13% 4 23% 40% 17% 3	1040
	11th to 20th	Night	14% 6% 25% 36% 18% 2	987
	21st to end	Night	18% 7% 24% 35% 14% 2	928
February	1st to 10th	Night	13% 4 23% 36% 21% 4	720
	11th to 20th	Night	13% 3 20% 42% 19% 2	704
	21st to end	Night	6% 3 24% 40% 23% 4	592
March	1st to 10th	Night	10% 4 23% 35% 23% 4	720
	11th to 20th	Night	14% 4 20% 43% 18% 2	720
	21st to end	Night	13% 4 19% 36% 25% 3	792
April	1st to 10th	Night	11% 4 19% 39% 24% 3	708
	11th to 20th	Night	13% 4 21% 34% 24% 4	516
	21st to end	Night	16% 2 23% 37% 20% 2	360
May	1st to 10th	Night	14% 5% 16% 38% 26% 3	360
	11th to 20th	Night	10% 5% 23% 35% 25% 3	354
	21st to end	Night	17% 2 11% 40% 27% 3	389
June	1st to 10th	Night	14% 4 11% 41% 29%	360
	11th to 20th	Night	20% 3 13% 33% 28% 4	360
	21st to end	Night	12% 3 14% 38% 28% 5%	360
July	1st to 10th	Night	14% 3 13% 35% 32% 3	350
	11th to 20th	Night	12% 3 9% 39% 34% 4	348
	21st to end	Night	14% 2 11% 35% 35% 4	394
August	1st to 10th	Night	10% 2 7% 34% 39% 8%	358
	11th to 20th	Night	6% 2 17% 47% 25% 3	356
	21st to end	Night	16% 2 15% 41% 24% 3	517
September	1st to 10th	Night	18% 2 13% 37% 26% 4	688
	11th to 20th	Night	11% 3 17% 40% 27% 3	720
	21st to end	Night	13% 6% 26% 35% 17% 4	720
October	1st to 10th	Night	15% 6% 21% 39% 17% 2	720
	11th to 20th	Night	14% 6% 22% 38% 18% 3	720
	21st to end	Night	19% 8% 19% 38% 15% 2	792
November	1st to 10th	Night	17% 7% 23% 36% 16% 2	877
	11th to 20th	Night	14% 8% 25% 39% 13% 1	950
	21st to end	Night	14% 6% 27% 40% 12% 2	963
December	1st to 10th	Night	14% 5% 27% 36% 14% 3	1040
	11th to 20th	Night	14% 5% 25% 38% 15% 2	1040
	21st to end	Night	11% 4 23% 38% 21% 3	1144

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